Stairway

ABSTRACT

For the purpose of providing a staircase which has a lightweight structure, high efficiency in manufacturing and constructing, and creates a sense of lightness in weight, a staircase is composed with a pair of right and left stringers made of truss structural members ( 10 ), and treads ( 12 ). The truss structural members ( 10 ) are composed of the upper chord members ( 1 ) and the lower chord members ( 2 ) inclined with the slope of the staircase, and a plurality of lattice members ( 4 ) for linking the upper chord members ( 1 ) and the lower chord members ( 2 ), and between the truss structural members ( 10 ) are fixed a plurality of linking members ( 11 ) which are laid horizontally at each riser height and on which the treads ( 12 ) are fixedly supported.

TECHNICAL FIELD

The present invention relates to a staircase.

BACKGROUND ART

Conventionally, there have been various forms to support the treads of astaircase. In the case of a staircase made of wood or steel, the treadsare generally supported by stringers (including open stringers in thepresent specification). The stringers, which must support a heavy loadfrom the treads, are composed of large, thick members such as channelsteel or I-shaped steel in the case of a steel staircase, for example.

However, in conventional staircases, the heaviness of the stringersrequires a lot of work in carrying and constructing. Furthermore, thestringers differ in length and shape, depending on the installingrequirements including the number of steps in the staircase and theslope of the staircase, which makes it difficult to manufacturestringers efficiently.

Large and heavy members such as channel steel or I-shaped steel are usednot only for staircase stringers but also for other architecturalstructural members; however, using such members at a noticeable positionof a constructing structure creates an oppressive impression because oftheir heaviness, and also is poor in design.

In this context, the published examined utility model application No.4-21389 discloses a staircase with a simplified appearance, whichdisposes the treads inside between a pair of right and left side framesformed in a truss design. This staircase is composed of a pair of rightand left side frames formed in a truss design; linking members forlinking the lower chord members on both side frames; handrails which arelocated above the side frames and linked to them via linking members andwhich are arranged in parallel along the upper chord members of the sideframes; and treads laid inside between both side frames. And in order toprevent lateral buckling of the staircase, each end part of the upperchord members of the side frames and each end part of the handrails arebent outwards so as to have bent parts.

However, in this staircase, the handrails serve as structural members tomaintain the strength of the staircase; the treads are supported by thelower chord members of the side frames; and the upper chord members ofthe side frames are located above the treads, that is, at the height ofthe handrails. Therefore, this staircase is not suitable as a staircasedispensable with handrails. For example, if this staircase isconstructed along a wall face, the side frame is arranged right besidethe wall face and also above the treads, which rather spoils theappearance of the staircase. Additionally, the handrails of thestaircase which could be designed comparatively freely must serve asstructural members, thereby causing restrictions in design.

Also in the aforementioned staircase, the upper chord members and thehandrails are provided with bent parts to improve the strength; however,the handrails are arranged along the upper chord members of the rightand left side frames, making it impossible to link the upper cordmembers with each other, thereby limiting any improved strength of thestaircase as a whole. In addition, forming the bent parts requiresbending work, which inevitably is troublesome.

Furthermore, it is difficult to manufacture the bent parts efficientlybecause they must be processed in accordance with different installingrequirements such as the number of steps and the slope of the staircase.

Therefore, the present invention has an object of providing a staircasehaving a lightweight structure and giving a light impression, andanother object of providing a staircase having high strength and highefficiency in productivity and workability.

DISCLOSURE OF THE INVENTION

In order to solve such problems, the invention according to claim 1 is astaircase composed of: a pair of right and left stringers composed of atruss structural members; and treads, wherein the truss structuralmembers are each composed of: an upper chord member and a lower chordmember which are inclined with the slope of the staircase; and aplurality of lattice members for linking the upper chord member and thelower chord member.

According to this staircase, the stringers for supporting the treads arecomposed of truss structural members, which can make the staircase havea lightweight structure. In addition, unlike staircases made of heavymembers such as channel steel or I-shaped steel, staircase with a senseof lightness in weight and openness can be constructed, without giving asense of oppression even when it is installed indoors.

The invention according to claim 2 is the staircase according to claim1, wherein the truss structural members are linked to each other bytreads.

According to this staircase, since left and right truss structuralmembers are linked to each other by the treads, this improves torsionalrigidity and flexure rigidity in the side-to-side direction of theentire staircase, whereby twisting and rolling of the staircase whenpeople go up and down the staircase can be greatly reduced.

The invention according to claim 3 is the staircase according to claim1, wherein the plurality of lattice members include a plurality ofhorizontal lattice members disposed horizontally for each riser, and thetreads are supported by the horizontal lattice members.

According to this staircase, when the staircase is seen from the side,the tread is positioned between the upper chord member and the lowerchord member, so that a simplified appearance is realized.

The invention according to claim 4 is the staircase according to claim1, wherein the truss structural members are linked to each other via aplurality of linking members which are laid horizontally at each riserheight, and the treads are fixedly supported on the linking members.

According to this staircase, the light and left truss structural membersare linked to each other via the linking members, and as a result, thetorsional rigidity of the entire staircase and the flexural rigidity theside-to-side direction are improved, which greatly reduces thedevelopment of twisting or rolling of the staircase when people aregoing up and down the staircase.

The invention according to claim 5 is the staircase according to claim4, wherein the linking members adjacent to each other in the heightdirection are linked to each other.

According to this staircase, since the plurality of linking members areintegrated by being linked to each other in the height direction, when aload in the side-to-side direction is applied to one of the treads(linking members), this load is divided among other linking members.Therefore, for example, the development of twisting or rolling whenpeople go up and down the staircase is significantly reduced.Furthermore, the linking members adjacent to each other in the heightdirection are preferably linked to each other by a flat plate memberwith high rigidity in the side-to-side direction. The use of the flatplate member more efficiently improves the rigidity in the side-to-sidedirection of the staircase.

The invention according to claim 6 is the staircase according to any oneof claims 1 through 5, wherein the upper chord member and the lowerchord member are each provided with node members, and the latticemembers are joined with the node members.

According to this staircase, the staircase can be constructed just byjoining the lattice members with the node members installed in the upperchord members and the lower chord members. It is preferable that thenode members are installed on the bottom faces of the upper chordmembers or the top faces of the lower chord members. This enables thenode members to be installed regardless of the inner shapes of the upperchord members and the lower chord members, so that the inner shapes ofthe upper chord members and the lower chord members can be determined asdesired.

The invention according to claim 7 is the staircase according to claim6, wherein the node members are column-shaped and each have linkinggrooves formed on an outer surface thereof; the lattice members eachhave linking end parts formed on both ends; and the linking groove andthe linking end parts have notches to be engaged with each other, andnodes are formed by press fitting the linking end parts into the linkinggrooves.

According to this staircase, the linking end parts formed on both endsof the lattice members can be press fit into the linking grooves formedon the outer faces of the node members to join the lattice members andthe node members, which facilitates the constructing of the staircase.Furthermore, the notches formed on each of the linking grooves and thelinking end parts are engaged with each other, which prevents thelattice members from moving in the axial direction.

The invention according to claim 8 is the staircase according to claim6, wherein at least either the upper chord members or the lower chordmembers are continued in the direction of the staircase inclination andformed of members having groove parts opened to the lattice member side,and node members are attached inside the groove parts.

According to this staircase, either the upper chord members or the lowerchord members are continued in the staircase direction and the nodemembers are attached inside the upper chord members or the lower chordmembers, so that a simplified appearance can be obtained. Although thenode members are attached inside the upper chord members or the lowerchord members, the bottom faces of the upper chord members or the topfaces of the lower chord members are opened, so that the lattice memberscan be linked to the node members. Furthermore, the members can beattached with lid members for closing the openings. Thereby, since theopenings of the members forming the upper chord members and the lowerchord members are closed by lid members, dust accumulation inside themembers is prevented and the appearance is also improved.

The invention according to claim 9 is the staircase according to any oneof claims 1 through 5, wherein the truss structural members are eachcomposed of node members each disposed at a node point; and framemembers for linking adjacent node members.

According to this staircase, the truss structural members are composedby linking a plurality of frame members having the same length as thedistance between adjacent node points, which facilitates the control ofthe length of the truss structural members. Since the upper chordmembers and the lower chord members are also formed by linking aplurality of frame members, their whole length can be controlled just bychanging the length of the frame members to be linked (changing theriser height and the depth of the treads) or the number of steps. Whenthe plane shape of a staircase is modified like in a spiral staircase,all that must be done is to change the axial direction of the framemembers adjacent in the longitudinal direction of the truss structuralmembers so as to join the frame members with the node members. Thus,even a curved staircase can use the same frame members as a straightstaircase, which provides high production efficiency.

The invention according to claim 10 is the staircase according to claim9, wherein the node members are column-shaped and each have linkinggrooves on an outer surface thereof; the frame members each have linkingend parts on both ends; and the linking grooves and the linking endparts have notches to be engaged with each other, and nodes are formedby press fitting the linking end parts into the linking grooves.

According to this staircase, the linking end parts formed on both endsof the frame members can be press fit into the linking grooves formed onthe outer faces of the node members to join the frame members and thenode members, which facilitates the constructing of the staircase.Furthermore, the notches formed on each of the linking grooves and thelinking end parts are engaged with each other, which prevents the framemembers from moving in the axial direction.

The invention according to claim 11 is the staircase according to claim9 further comprising a reinforcing member arranged along at least one ofthe upper chord member and the lower chord member, the reinforcingmember being fixed with at least to three of the node members.

According to this staircase, in at least one of the upper chord memberand the lower chord member, the plurality of node members are integratedvia the reinforcing member, so that flexure rigidity in the out-of-planedirection of the truss structural members is improved, resulting indeformation reduction in the out-of-plane direction. This greatlyreduces the rolling of the staircase caused by load affecting theside-to-side direction of the staircase. As a result, the members tolink the right and left truss structural members can be omitted or madelighter weight, thereby providing a simplified appearance. Designing thereinforcing member flat-shaped can facilitate its production andinstallment. Shaping the reinforcing member like the letter L or agroove can provide a simple design because it covers the frame memberscomposing the upper chord members or the lower chord members, and alsoimproves vertical rigidity.

The invention according to claim 12 is the staircase according to anyone of claims 1 through 5, wherein at least either between the right andleft upper chord members or between the right and left lower chordmembers, a plate member is attached.

According to this staircase, the right and left truss structural membersare integrated by the plate member, and shearing deformation of theplane formed by the two upper chord members or lower chord members isreduced, so that the development of twisting or rolling of the trussstructural members when people go up and down the staircase is greatlyreduced.

The invention according to claim 13 is the staircase according to anyone of claims 1 through 5, further comprising handrails positioned abovethe side end parts of the treads, and balusters that have lower endsjoined with the truss structural members and support the handrails.

This staircase is provided with handrails above the side end parts ofthe treads. By bending the lower portions of the balusters supportingthe handrails orthogonally to the handrails, rigidity against a loadthat pushes down the handrail sideward is increased.

The invention according to claim 14 is a staircase comprising a pair ofright and left truss structural members which are inclined with theslope of the staircase and a plurality of treads disposed between thetruss structural members, wherein each truss structural member iscomposed of an upper chord member having a plurality of column-shapedupper node members provided in series in the direction of the staircaseinclination, a lower chord member having a plurality of column-shapedlower node members provided in series in the direction of the staircaseinclination, and lattice members that link the upper chord member andthe lower chord member to each other, each upper node member and eachlower node member are disposed so that the axes thereof are orthogonalto the truss plane of the truss structural member, and on the outercircumferential faces thereof, a plurality of linking grooves are formedalong the axes, and the lattice member has flat-shaped linking end partsthat can fit into the linking grooves on both ends, one of the linkingend parts is fitted into the linking groove of the upper node member,the other one of the linking end parts is fitted into the linking grooveof the lower node member, and the ends of each tread are fixed to theside end face of the upper node member and the side end face of thelower node member.

As compared with the conventional staircases composed of heavy membersmade of channel steel or I-shaped steel, the above-described staircaseis structured so that the treads are supported by truss structuralmembers that have lightweight structures and look light in weight,thereby providing a sense of openness and creating no sense ofoppression even if the staircase is installed indoors. In addition, thestaircase of the invention is structured so that the side end parts ofthe treads are fixed to the side end faces of the upper node members andthe side end faces of the lower node members, whereby the side end facesof the treads are positioned within the side faces of the trussstructural members, thereby providing a very simplified appearance.

Furthermore, the upper chord member and the lower chord member of eachtruss structural member are linked to each other by the treads. Namely,since the upper chord member and the lower chord member are securelyintegrated by the lattice members in addition to the treads, therigidity of each truss structural member is very high. Furthermore, as aresult, the upper node members and the lower node members are linked toeach other between the right and left truss structural members by thetreads, so that displacement and deformation in the out-of-planedirection of the truss planes are restricted by each other. Namely,since the upper chord members are linked to each other and the lowerchord members are linked to each other by the treads between the rightand left truss structural members and shearing deformation of the planeformed by the right and left upper chord members and the plane formed bythe right and left lower chord members are restrained, respectively, asa result, the development of twisting and rolling when people go up anddown the staircase is greatly reduced.

The joining between the lattice members and the node members is carriedout only by fitting the linking end parts of the lattice members thathave been processed so as to be fitted into the linking grooves formedon the outer circumferential face of the node members, without requiringwelding or special tools, thereby providing high workability. Inaddition, since the node members are disposed so that the axes thereofare orthogonal to the truss planes of the truss structural members, theaxes of the node members and the axes of the lattice members are alwaysorthogonal to each other regardless of the slope of the staircase.Namely, regardless of the slope of the staircase, the linking end partsof the lattice members are formed in the direction orthogonal to theaxes of the lattice members, thereby enabling mass production andproviding high productivity. Since the axes of the node members areorthogonal to the truss planes, the truss structural members have astrong axis direction in the out-plane direction (side-to-side directionof the staircase) and have high strength against an external force ordeformation from the out-of-plane direction.

The invention according to claim 15 is the staircase according to claim14, wherein the upper chord members have upper frame members providedbetween the upper node members adjacent to each other in the directionof the staircase inclination, and the upper frame members have, on theirboth ends, flat-shaped linking end parts that can be fitted into thelinking grooves of the upper node members, and the linking end parts arefitted into the linking grooves of the upper node members.

According to this staircase, the lengths of the upper chord members canbe easily adjusted. Namely, since the upper chord member is constructedby providing a plurality of upper frame members in series in thedirection of the staircase inclination and linking the upper framemembers adjacent to each other in the direction of the staircaseinclination to each other by the upper node members, the length of theupper chord member can be adjusted only by increasing or reducing thenumber of upper frame members to be linked to each other.

Furthermore, the joining between the upper frame members and the uppernode members is carried out only by fitting the linking end parts of theupper frame members which have been processed so as to be fitted in thelinking grooves, without requiring welding or special tools, therebyproviding high workability. In addition, since the upper node membersare disposed so that the axes thereof are orthogonal to the truss planesof the truss structural members, so that the axes of the upper nodemembers and the axes of the upper frame members are always orthogonal toeach other regardless of the slope of the staircase. Namely, regardlessof the slope of the staircase, the upper frame members are formed sothat the linking end parts thereof are orthogonal to the axes of theupper frame members, and this structure can be commonly used forstaircases with various slopes and provides high productivity.

The invention according to claim 16 is the staircase according to claim14, wherein the lower chord members have lower frame members disposedbetween the lower node members adjacent to each other in the directionof the staircase inclination, and the lower frame members have, on theirboth ends, flat-shaped linking end parts that can be fitted into thelinking grooves of the lower node members, and the linking end partshave been fitted into the linking grooves of the lower node members.

According to this staircase, the lengths of the lower chord members canbe easily adjusted. Namely, since the lower chord member is constructedby providing lower frame members in series in the direction of thestaircase inclination and linking the lower frame members adjacent toeach other in the direction of the staircase inclination by the lowernode members, the length of the lower chord member can be adjusted onlyby increasing or reducing the number of lower frame members to be linkedto each other.

Furthermore, the joining between the lower frame members and the lowernode members is carried out only by fitting the linking end parts of thelower frame members that have been processed so as to be fitted intolinking grooves formed on the side faces of the lower node members,without requiring welding or special tools, thereby providing highworkability. In addition, since the lower node members are disposed sothat the axes thereof are orthogonal to the truss planes of the trussstructural members, the axes of the lower node members and the axes ofthe lower frame members are always orthogonal to each other regardlessof the slope of the staircase. Namely, the lower frame members areformed so that their linking end parts are orthogonal to the axes ofthese lower frame members, this structure can be commonly used forstaircases with various slopes and provides high productivity.

The invention according to claim 17 is the staircase according to claim14, wherein the upper chord member has an upper through member having alength from the upper end to the lower end of the upper chord member,and the upper through member is attached to the side end faces of theupper node members.

According to this staircase, the upper chord member has an upper throughmember and the upper through member is attached to the side end faces ofthe plurality of upper node members, thereby reinforcing the strength inthe weak axis direction of the truss structural member. Therefore, thetruss structural member becomes high in bending rigidity in both theside-to-side direction and the vertical direction, and the developmentof rolling and flexure when people go up and down is greatly reduced.

The invention according to claim 18 is the staircase according to claim14, wherein the lower chord member has a lower through member having alength from the upper end to the lower end of the lower chord member,and the lower through member is attached to the side end faces of thelower node members.

According to this staircase, since the lower chord member has a lowerthrough member and the lower chord member is attached to the side endfaces of the plurality of lower node members, it thereby reinforces thestrength in the weak axis direction of the truss structural member.Therefore, the truss structural members become high in bending rigidityin both the side-to-side direction and the vertical direction, and thedevelopment of rolling and flexure when people go up and down thestaircase is greatly reduced.

The invention according to claim 19 is the staircase according to claim14, wherein the upper node members and the lower node members arepositioned at the same heights, and tread receiving members are fixed tothe side end faces of the upper node members and the side end faces ofthe lower node members, and the treads are fixed to the tread receivingmembers.

According to this staircase, the work for attaching the treads becomeseasy. Furthermore, by employing the method in which the treads areattached via the tread receiving members, it is possible to cope withthe case where the upper node members and the lower node members are notpositioned at the same heights only by changing the shape or theattachment position of the tread receiving member. Furthermore, the topfaces of the treads become horizontal without fail only by attaching thetreads along the upper node members and the lower node members, and thismakes the work for attaching the treads easy.

The invention according to claim 20 is the staircase according to anyone of claims 14 through 19, further comprising handrails positionedabove the side end parts of the treads, and balusters the lower ends ofwhich are joined to the truss structural member, and supporting thehandrails.

This staircase has handrails above the side end parts of the treads.Furthermore, by curving the lower parts of the balusters supporting thehandrails in the directions orthogonal to the handrails, the resistanceagainst loads that press down the handrails sideward is increased.

The invention according to claim 21 is a staircase in which treads aresupported by a space truss structural member inclined with the slope ofthe staircase, wherein the space truss structural member is formed bylinking a plurality of upper chord members linked to each other withlower chord members located below the midpoint of the adjacent ones ofthe upper chord members via lattice members.

According to this staircase, the lower chord members are arranged belowthe midpoint of adjacent ones of the upper chord members; for examplewhen there are three upper chord members, two lower chord members areprovided. In this case, when seen from the direction of the slope of thestaircase, the space truss structural members look trapezoidal, whichcan provide a simplified appearance. Furthermore, the space trussstructural member has a sense of lightness in weight and openness, andcreates no sense of oppression even if the staircase is installedindoors. In addition, the adjacent upper chord members are linked andintegrated with each other, and as a result, in the space trussstructural member, the torsional rigidity of and the flexural rigiditythe side-to-side direction are high, and the twisting or rolling of thestaircase developed when people are going up and down the staircase isslight. Furthermore, the handrails can be designed as desired becausethey are not structural members in the main body of the staircase.

In addition, the staircase is a lighter-weight structure thanconventional staircases which use heavy members such as channel steel orI-shaped steel, thereby facilitating handling during construction.

When there are two upper chord members, a single lower chord member isused, which makes the space truss structural member look like aninverted triangle when viewed from the direction of the slope of thestaircase.

The invention according to claim 22 is the staircase according to claim21, wherein the space truss structural member further comprises a secondlower chord member below the aforementioned lower chord members, and thelower chord members and the second lower chord member are linked to eachother by lattice members.

According to this staircase, the second lower chord member furtherdisposed below the lower chord members increases the bending rigidity ofthe space truss structural member. Furthermore, by disposing the secondlower chord member and the lattice members that link the lower chordmembers and the second lower chord member to each other only at themidpoint between the upper floor and the lower floor, flexure of thetruss structural members at the central section of the upper and lowerfloors where the bending moment increases is restrained.

The invention according to claim 23 is the staircase according to claim21 or 22, wherein the upper chord member and the lower chord member areeach formed by linking a plurality of frame members via node members.

According to this staircase, since the upper chord members and the lowerchord members are linked via the plurality of frame members, the length(the number of steps) of the staircase as a whole can be easilycontrolled by increasing or decreasing the number of frames to belinked.

The invention according to claim 24 is the staircase according to claim23, wherein a reinforcing member is disposed along at least either oneof the upper chord member or the lower chord member of the space trussstructural member, and the reinforcing member is fixed to three or moreof successive node members.

According to this staircase, in at least either one of the upper chordmember or the lower chord member, the plurality of node members areintegrated by the reinforcing member and the bending rigidity in theside-to-side direction of the upper chord member is increased, as aresult, deformation in the side-to-side direction is restrained.Thereby, rolling of the staircase caused by the load applied in theside-to-side direction when people go up and down the staircase isgreatly reduced. Furthermore, since the linking frame members that linkthe adjacent upper chord members to each other can be lightened inweight or reduced in number, the appearance of the entire staircase issimplified. Furthermore, by forming the reinforcing member to be flat,an L shape, or a groove shape, it becomes easy to manufacture and attachthe reinforcing member, and furthermore, when the reinforcing member isformed into an L shape or a groove shape, the frame members that formthe upper chord members or the lower chord members are concealed,thereby providing a simple design and improving the vertical rigidity ofthe space truss structural member. Furthermore, when the reinforcingmember has a hollow part at least at a part of its section, thesectional properties thereof are improved, so that the space trussstructural member reinforced by this reinforcing member is improved inrigidity in not only the side-to-side direction but also the verticaldirection.

The invention according to claim 25 is the staircase according to claim23, wherein the lattice members and the frame members each have linkingend parts on both ends; on outer surfaces of the node members are formedlinking grooves into which the linking end parts can be fit; and thelinking end parts are fit into the linking grooves.

According to this staircase, the joining between the frame members andthe node members, or the joining between the lattice members and thenode members can be carried out only by fitting the linking end parts ofthe aforementioned members which have been processed so as to be fittedinto the linking grooves formed on the side faces of the node members,without requiring welding or special tools, thereby proving high inworkability.

The invention according to claim 26 is the staircase according to claim25, wherein adjacent ones of the upper chord members are linked to eachother via linking frame members, and the linking frame members each havelinking end parts on both ends, the linking end parts being fit into thelinking grooves of the node members. According to this staircase, thejoining between the node members and the linking frame members can becarried out only by fitting the linking end parts formed on both ends ofthe linking frame members into the node members having the linkinggrooves, without requiring welding or special tools, thereby provinghigh in workability.

The invention according to claim 27 is the staircase according to claim21 or 22, wherein the upper chord members have connection pieces thatproject toward the lower chord members and the lower chord members haveconnection pieces that project toward the upper chord members, thelattice members have flat end parts on their both ends, and one of theflat end parts is joined to the connection piece of the upper chordmember, and the other flat end part is joined to the connection piece ofthe lower chord member.

According to this staircase, since the linking between the upper chordmembers and the lower chord members is carried out only by joining theflat end parts of the lattice members to the connection pieces of theupper chord members and the connection pieces of the lower chord membersprojecting in the connection directions of the lattice members, the workfor assembling the space truss structural member becomes easy.

The invention according to claim 28 is the staircase according to claim27, wherein the upper chord members adjacent to each other are linked toeach other by the linking frame members, the linking frame members haveflat end parts on both ends thereof, each of the upper chord members hasa connection piece projecting toward another adjacent upper chordmember, and the flat end part of the linking frame member is joined tothe connection piece.

According to this staircase, since the linking between the upper chordmembers is carried out only by joining the flat end parts of the linkingframe members to the connection pieces of the upper chord membersprojecting in the connection directions of the linking frame members,the work for assembling the space truss structural member becomes easy.

The invention according to claim 29 is the staircase according to claim26 or 28, wherein the linking frame members include linking diagonalmembers which are diagonal to each of the upper chord members.

According to this staircase, the linking diagonal members arrangeddiagonally between the upper chord members can reduce the shearingdeformation on the top face of the space truss structural member. Inother words, in the space truss structural member, the torsionalrigidity and the flexural rigidity the side-to-side direction areimproved, which greatly reduces the development of twisting or rollingof the staircase when people are going up and down the staircase.

The invention according to claim 30 is the staircase according to claim21 or 22, wherein the upper chord member is formed of a member having agroove part opened at its lower chord member side, where the groove parthouses the node members, and the lower chord member is formed by linkinga plurality of frame members by node members, and the lattice member andthe frame member have linking end parts on their both ends, and on theouter faces of the node members, linking grooves into which the linkingend parts can fit are formed, and the linking end parts are fitted intothe linking grooves.

According to this staircase, the upper chord members are formed ofmembers having groove parts and the groove parts house node members, sothat a simplified appearance can be obtained. Furthermore, the linkingbetween the lattice members and the node members is carried out only byfitting the linking end parts of the members processed so as to befitted into the linking grooves formed on the side faces of the nodemembers, without requiring welding or special tools, thereby providinghigh workability.

The invention according to claim 31 is the staircase according to claim21 or 22, wherein adjacent ones of the upper chord members are linked toeach other via brackets for supporting the treads.

According to this staircase, the adjacent upper chord members are linkedvia the brackets, which further reduces the displacement and deformationthe side-to-side direction of the space truss structural member. Sincethe flexure rigidity the side-to-side direction of the staircase as awhole is improved, rolling of the staircase when people are going up anddown the staircase can be greatly reduced. Supporting the center part ofthe treads by the brackets reduces the flexure on the treads. Therefore,the strength of the treads themselves can be small, which extends therange of choices in the structure and material of the treads. By formingtread supporting faces to support the treads on the top faces of thebrackets; forming attachment faces for being fixed on the upper chordmembers on the bottom faces of the brackets; and inclining theattachment faces with the slope of the staircase with respect to thetread supporting faces, the tread supporting faces become horizontalwhen installed on the top faces of the upper chord members. Thisfacilitates the installing work of the treads, thereby improving theconstructing efficiency.

The invention according to claim 32 is the staircase according to claim21 or 22, wherein the upper chord members adjacent to each other arelinked to each other by a plate member.

According to this staircase, since the adjacent upper chord members areintegrated by the plate member, shearing deformation of the plane formedby the adjacent upper chord members, that is, the top face of the spacetruss structural member is reduced. Namely, since the torsional rigidityand the bending rigidity in the side-to-side direction of the spacetruss structural member are increased by the plate member, thedevelopment of twisting and rolling of the space truss structural memberwhen people go up and down the staircase can be further restrained. Inthis case, the plate member may be extrusion molded integrally with theupper chord members. Thereby, since the adjacent upper chord members areintegrated in advance, the number of parts is reduced and constructionof the space truss structural member becomes easy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the staircase according to the firstembodiment of the present invention.

FIG. 2 is a side view of the staircase shown in FIG. 1.

FIG. 3 is an enlarged side view of the staircase shown in FIG. 1.

FIG. 4 is a front view of the staircase shown in FIG.

FIG. 5(a) is a plan view of the treads, and FIG. 5(b) is a front view ofthe same.

FIG. 6(a) is a perspective view of the frame members composing the upperchord members and the lower chord members, FIG. 6(b) is a perspectiveview of the frame members composing the lattice members, and FIG. 6(c)is a side view of the frame member shown in FIG. 6(b).

FIG. 7(a) is a perspective view of the linking members, and FIG. 7(b) isan end view of the same.

FIG. 8 is a perspective view of an example of the node members providedto the upper chord members.

FIG. 9 is a perspective view of an example of the node members providedto the lower chord members.

FIG. 10 is a plan view of the node members.

FIG. 11(a) is an enlarged side view of the handrail, and FIG. 11(b) is afurther enlarged view of FIG. 11(a).

FIG. 12(a) and FIG. 12(b) are front views of the balusters, and FIG.12(c) is an enlarged front view of FIG. 12(b).

FIG. 13(a) is a cross sectional view of the joint part between thehandrail and the baluster, and FIG. 13(b) is a top view of the same.

FIG. 14 is a perspective view of the staircase according to the secondembodiment of the present invention.

FIG. 15 is a side view of the staircase shown in FIG. 14.

FIG. 16 is an enlarged side view of the staircase shown in FIG. 14.

FIG. 17 is a front view of the staircase shown in FIG. 14.

FIG. 18 is a plan view of the treads, and FIG. 18(b) is a crosssectional view of the same.

FIG. 19 is a perspective view of the horizontal lattice members.

FIG. 20 is a perspective view of the staircase according to the thirdembodiment of the present invention.

FIG. 21(a) is a simplified plan view of the frame members and the nodemembers in the case of forming a curved truss structural member, FIG.21(b) is a plan view of the frame member shown in FIG. 21(a).

FIG. 22(a) and FIG. 22(b) are perspective views of other examples of thestaircase according to the third embodiment.

FIG. 23 is a side view of the staircase according to the fourthembodiment of the present invention.

FIG. 24 is an enlarged side view of the staircase where is partly brokenshown in FIG. 23.

FIG. 25(a) is a cross sectional view taken along the line X-X of FIG.24, FIG. 25(b) is a cross sectional view taken along the line Y1-Y1 ofFIG. 24, and FIG. 25(c) is an end view taken along the line YC-YC ofFIG. 24.

FIG. 26(a) is a cross sectional view taken along the line Y2-Y2 of FIG.24 and FIG. 26(b) is a cross sectional view taken along the line Y3-Y3of FIG. 24.

FIG. 27 is a plan view of the treads, and FIG. 27(b) is a front view ofthe same.

FIG. 28 is a plan view of another type of tread, and FIG. 28(b) is afront view of the same.

FIG. 29 is a cross sectional view of another example of the upper chordmembers of the staircase according to the fourth embodiment, and FIG.29(b) is a cross sectional view of another example of the lower chordmembers.

FIG. 30 is across sectional view of the upper chord members of thestaircase according to the fifth embodiment of the present invention.

FIG. 31 is an enlarged side view of the staircase according to the fifthembodiment of the present invention.

FIG. 32 is a side view of the staircase according to the sixthembodiment of the present invention.

FIG. 33 is an enlarged side view of the staircase where is partly brokenshown in FIG. 32.

FIG. 34(a) is a cross sectional view taken along the line Y5-Y5 of FIG.32, and FIG. 34(b) is a cross sectional view of the linking members.

FIG. 35(a) is an exploded perspective view of the truss structuralmembers, and FIG. 35(b) is a perspective view showing the state where anupper reinforcing member and a lower reinforcing member are installed inone of the truss structural members.

FIG. 36 is an exploded perspective view of the staircase according tothe sixth embodiment of the present invention.

FIG. 37(a) is a view showing another cross sectional shape of the upperreinforcing members and the lower reinforcing members, and FIG. 37(b) isa cross sectional view showing the state where the upper reinforcingmember is exclusively installed.

FIG. 38 is a perspective view of the staircase according to the seventhembodiment of the present invention.

FIG. 39 is a perspective view showing the staircase according to theeighth embodiment of the present invention.

FIG. 40 is a perspective view of another example of the staircaseaccording to the eighth embodiment of the present invention.

FIG. 41 is a perspective view of a staircase according to the ninthembodiment of the invention.

FIG. 42 is a side view of the staircase shown in FIG. 41.

FIG. 43(a) is an enlarged view of FIG. 42, which is partly broken, andFIG. 43(b) is a view seen from the direction of the arrows A-A of FIG.43(a).

FIG. 44(a) is a perspective view describing a method for joining theupper node members (upper hubs) and the upper frame members, and FIG.44(b) is a perspective view describing a method for joining the lowernode members (lower hubs) and the lower frame members.

FIG. 45 is a cross sectional view showing the state of joining of theupper node member (upper hub), the upper frame members, and the latticemembers.

FIG. 46(a) is a perspective view showing the upper frame member, andFIG. 46(b) is a side view of FIG. 46(a).

FIG. 47(a) is a view seen from the direction of the arrows B-B of FIG.43, and FIG. 47(b) is a view seen from the direction of the arrows C-Cof FIG. 43.

FIG. 48(a) is an enlarged view of the lower part of FIG. 42, FIG. 48(b)is across sectional view along D-D of FIG. 48(a), and FIG. 48(c) is aview seen from the direction of the arrows E-E of FIG. 48(a).

FIG. 49(a) and FIG. 49(b) are exploded perspective views describingconstruction procedures of the staircase according to the ninthembodiment.

FIG. 50 is an exploded perspective view describing constructionprocedures of the staircase according to the ninth embodiment.

FIG. 51 is a perspective view showing another example of the staircaseaccording to the ninth embodiment.

FIG. 52(a) is an enlarged side view showing still another example of thestaircase according to the ninth embodiment, and FIG. 52(b) is acrosssectional view along F-F of FIG. 52(a).

FIG. 53(a) and FIG. 53(b) are perspective views showing modifiedexamples of the tread receiving members.

FIG. 54(a) and FIG. 54(b) are perspective views showing still anothermodified example of the tread receiving members.

FIG. 55(a) and FIG. 55(b) are perspective views showing a modifiedexample of the treads.

FIG. 56 is a side view showing an example for coping with a case wherethe slope of the staircase is changed.

FIG. 57 is a perspective view of the staircase as a whole according tothe tenth embodiment of the present invention.

FIG. 58 is a front view of the staircase shown in FIG. 57.

FIG. 59 is a side view of the staircase shown in FIG. 57.

FIG. 60 is an enlarged side view of the staircase shown in FIG. 59.

FIG. 61 is an exploded perspective view of the staircase of the tenthembodiment.

FIG. 62(a) is a view seen from the direction of the arrows X1-X1 of FIG.59, and FIG. 62(b) is a view seen from the direction of the arrows X2-X2of FIG. 62(a).

FIG. 63(a) is a perspective view of the frame members and the linkingframe members, FIG. 63(b) is a plan view of the same, FIG. 63(c) is aperspective view of the lattice members, and FIG. 63(d) is a plan viewof the same.

FIG. 64 is a perspective view to explain the node members (hubs).

FIG. 65 is a plan view of the node members shown in FIG. 64.

FIG. 66(a) is a cross sectional view taken along the line X3-X3 of FIG.59, and FIG. 66(b) is a view seen from the direction of the arrows X4-X4of FIG. 59.

FIG. 67(a) is a perspective view of the brackets, and FIG. 67(b) is aside view of the same.

FIG. 68(a), FIG. 68(b), and FIG. 68(c) are side views of the supportshoes.

FIG. 69 is an exploded perspective view of the staircase according tothe eleventh embodiment of the present invention.

FIG. 70(a) is a plan view showing the arrangement of the upper chordmembers and the linking frame members in a space truss structural membercomposing the staircase according to the eleventh embodiment of thepresent invention, FIG. 70(b) is a plan view showing the arrangement ofthe lower chord member and the lattice members of the same, and FIG.70(c) is a side view of the space truss structural member.

FIG. 71 is a side view of the staircase according to the eleventhembodiment of the present invention.

FIG. 72 is an enlarged side view of the staircase shown in FIG. 71.

FIG. 73 is an exploded perspective view of the staircase according tothe twelfth embodiment of the invention.

FIG. 74 is a view of the space truss structural member shown in FIG. 73seen from the direction of the staircase inclination and the bracket andthe tread seen from the staircase front side.

FIG. 75 is a view of the space truss structural member of the staircaseaccording to the thirteenth embodiment of the invention seen from thedirection of the staircase inclination and the bracket and the treadseen from the staircase front side.

FIG. 76 is a side view relating to the staircase according to thethirteenth embodiment of the invention.

FIG. 77 is an exploded perspective view of the staircase according tothe fourteenth embodiment of the invention.

FIG. 78(a) and FIG. 78(b) are exploded perspective views of thestaircase according to the fifteenth embodiment of the invention.

FIG. 79(a) is a view of the space truss structural member of FIG. 78(b)seen from the direction of the staircase inclination and the bracket andthe tread seen from the staircase front side, FIG. 79(b) is a viewshowing a modified example of the staircase according to the fifteenthembodiment of FIG. 78(b).

FIG. 80(a), FIG. 80(b), and FIG. 80(c) are views showing other modifiedexamples of the staircase according to the fifteenth embodiment.

FIG. 81(a) and FIG. 81(b) are exploded perspective views of thestaircase according to the sixteenth embodiment of the invention.

FIG. 82 is a side view of the staircase shown in FIG. 81(a) and FIG.81(b).

FIG. 83(a) is a view seen from the direction of the arrows X7-X7 of FIG.82, FIG. 83(b) and FIG. 83(c) are views showing modified examples of thestaircase according to the sixteenth embodiment.

FIG. 84 is a perspective view partially omitting the staircase accordingto the seventeenth embodiment of the invention.

FIG. 85(a) is a view of the space truss structural member of FIG. 84seen from the direction of the staircase inclination, and FIG. 85(b) isa side view of FIG. 84.

FIG. 86 is a perspective view showing the linking frame member and thelattice member.

FIG. 87 is a perspective view partially omitting the staircase accordingto the eighteenth embodiment of the invention.

FIG. 88 is a view of the space truss structural member shown in FIG. 87seen from the direction of the staircase inclination.

BEST MODE FOR CARRYING OUT THE INVENTION

The preferable embodiments of the present invention will be described asfollows with the drawings.

First Embodiment

As shown in FIG. 1 through FIG. 4, the staircase according to a firstembodiment of the present invention is composed of truss structuralmembers 10 and 10, which are a pair of right and left stringers; aplurality of linking members 11 for linking the stringers; treads 12which are fixedly supported on the linking members 11; handrails 15which are located above the side end parts of the treads 12; andbalusters 13 and 14 for supporting the handrails 15. In addition, in thepresent embodiment, between the bottom ends of the truss structuralmembers 10 and the floor face 7 lower floor are disposed support shoes 6a and 6 b, and between the top ends of the truss structural members 10and the beam member 8 a upper floor are disposed support shoes 6 c.

The truss structural members 10, as shown in FIG. 2 and FIG. 3, are eachcomposed of an upper chord member 1 and a lower chord member 2 which areinclined with the slope of the staircase; and a plurality of latticemembers 4 for linking them. In the present embodiment, the upper chordmember 1 and the lower chord member 2 are each composed of a pluralityof frame members 3 linked to each other via hubs 5 which are nodemembers, the lattice members 4 being composed of the same members as theframe members 3. Thus, the truss structural members 10 are each composedof the plurality of frame members 3 and the hub 5 for linking them, theend parts of the frame members 3 being joined with the hubs 5 eacharranged at each node.

The frame members 3, as shown in FIG. 6(a), are each composed of atubular member having flat-shaped linking end parts 3 a formed at bothends thereof, the linking end parts 3 a having notches at their tips.The frame members 3 are extrusions of aluminum alloy, and the linkingend parts 3 a are formed by press working or the like. Since they arelong flattened in the axial direction of the hubs 5 (See FIG. 8 and FIG.9), the linking end parts 3 a have a joint structure strong against theexternal force in the axial direction of the hubs 5.

The lattice members 4 are composed of the same kind of members as theframe members 3, and as shown in FIG. 6(b) and 6(c), the tips of thelinking end parts 4 a are cut at an angle α (hereinafter referred to asthe coin angle α) with respect to the axial direction of the framemembers 3.

The hubs 5, as shown in FIG. 8 and FIG. 9, are column-shaped extrusionsor casts of aluminum alloy. The hubs 5 are each provided with aplurality of linking grooves 5 a carved on their outer surface alongtheir axial direction. The linking grooves 5 a have the same crosssectional shape as the tip parts of the linking end parts 3 a of theframe members 3 and the tip parts of the linking end parts 4 a of thelattice members 4, and their inner walls are provided with notches whichare formed to be engaged with the notches of the linking end parts 4 a(3 a). The hubs 5 arranged along the upper chord members 1 and the hubs5 arranged along the lower chord members 2 have almost the samestructure; however, they are shaped so as to be coincident with thenumber and angle of the members to be joined with the hubs 5. Forexample, the hubs 5 on the upper chord members 1 side have a heightwhich allows a lattice member 4, a frame member 3, and balusters 13 and14 to be press fit therein sequentially (the length in the direction ofthe linking grooves 5 a) (See FIG. 8), and the hubs 5 on the lower chordmembers 2 side have a height which allows a frame member 3 and a latticemember 4 to be press fit therein sequentially (See FIG. 9).

The linking end part 3 a of a frame member 3 is press fit into thelinking groove 5 a of a hub 5 from the upper-face side or the lower-faceside of the hub 5 so as to join the frame member 3 with the hub 5. Atthis time, as shown in FIG. 10, the notches formed on each of thelinking grooves 5 a and the linking end parts 14 a are engaged with eachother, so it never occurs that the frame member 3 is pulled out in theaxial direction.

The joint between the lattice members 4 and the hubs 5 is performed inthe same manner as above except that the lattice members 4 are joinedwith the linking grooves 5 a with an inclination of the coin angle αbecause the linking end parts 4 a of the lattice members 4 have aninclination of the coin angle α at their tips as shown in FIG. 6(c).

The linking members 11, as shown in FIG. 7(a) and 7(b), each haveflat-shaped linking end parts 11 a and a tread supporting part 11 b onwhich one of the treads 12 is fixedly supported and which ishorizontally laid between the right and left upper chord members 1 and 1(See FIG. 4). The distance between vertically adjacent ones of thelinking members 11, that is, the difference in height between two of thelinking members 11 adjacent in the height direction equals the height ofthe riser. The linking end parts 11 a have the same shape as the linkingend parts 3 a of the frame members 3, and can be press fit into thelinking grooves 5 a of the hubs 5. The linking members 11 are extrusionsof aluminum alloy, and the linking end parts 11 a are formed by pressworking or the like. The portions to be pressed are cut beforehand inorder to prevent the tread supporting parts 11 b from hindering thepress working. The top faces of the tread supporting parts 11 b aredisposed horizontally, whereas the linking grooves 5 a of the hubs 5(the axis of the hubs 5) into which the linking end parts 11 a are pressfitted are formed in the direction orthogonal to the direction of theslope of the staircase (See FIG. 7(b)), so the press working of thelinking end parts 5 a is performed in the direction rotated by an angleθ from the direction perpendicular to the top faces of the treadsupporting parts 11 b.

It is possible to link the lower chord members 2 and 2 on the right andleft sides with each other, although this is not illustrated. In thiscase, the linking members preferably have the same structure as theframe members 3, and when the lower chord members 2 and 2 are linked toeach other via the linking members, the linking end parts can be pressfit into the linking grooves 5 a of the hubs 5.

The treads 12, as shown in FIG. 5(a) and FIG. 5(b), are plate membersmade of wood or metal, and are fixed on the tread supporting parts 11 bwith screws, nails, or bolts.

The balusters 13, as shown in FIG. 12(a), are tubular members havingflat-shaped linking end parts 13 a at both ends, the linking end parts13 a having notches at their tips. The balusters 13 are extrusions ofaluminum alloy, and the linking end parts 13 a are formed by pressworking or the like. The tips of the linking end parts 13 a are shapedto form the coin angle α with the axial direction (See FIG. 11(a).

The balusters 14 are tubular members of which low parts have beensubjected to a bending process in such a manner as to be curved in thedirection orthogonal to the handrails (to the right side in FIG. 12(b)),that is, outwardly curved from the faces formed by the handrails 15 andthe balusters 13. At the both ends of the balusters 14 are formedflat-shaped linking end parts 14 a having notches at their tips. Thebalusters 14 are extrusions of aluminum alloy, and the linking end parts14 a are formed by press working or the like. Since the axial directionof the balusters 14 is different from the direction of the linkinggrooves 15 b of the handrails 15, the linking end parts 14 a on theupper end side of the balusters 14 are bent so as to form an angle β(hereinafter, bent angle β) with the axial direction of the balusters 14(See FIG. 12(c)), thereby matching the direction of the linking endparts 14 a with the direction of the linking grooves 15 b.

The handrails 15, as shown in FIG. 13(a), are each composed of a railmember 15 a having a linking groove 15 b formed on its bottom face, anda handrail cover 15 c for covering the rail member 15 a. The linkinggrooves 15 b have the same cross sectional shape as the linking endparts 13 a and 14 a on the upper end side of the balusters 13 and 14,and the inner walls of the linking grooves 15 b have notches which aresupposed to be engaged with the notches formed on the linking end parts13 a and 14 a. In FIG. 13(a), the reference symbol 15 d represents ajoint piece used to join a plurality of rail members 15 a together. Inthe case of a straight staircase as shown in FIG. 1, it is possible touse a single rail member for each hand rail; however, in the case of acurved staircase or when it is difficult to insert the linking end parts13 a and 14 a of the balusters 13 and 14 from the end parts of thelinking grooves 15 b, a plurality of short rail members 15 a can bejoined together via the joint pieces 15 d (See FIG. 13(b)).

FIG. 13(b) is a view seen from the direction of the arrow “b” of FIG.13(a) and shows the case where the staircase is curved as shown in FIG.20, FIG. 22(a), and FIG. 22(b) described later.

The following is a description regarding the construction process of thestaircase according to the first embodiment. In the followingdescription, the aforementioned members are assembled in sequence at abuilding site of the staircase; however, instead of this, it is alsopossible to assemble some units of members integrated in considerationof efficiency in carrying and constructing.

First, the truss structural members 10 and 10 are laid between the floorboard 7 lower floor and the beam member 8 a upper floor with aprescribed distance between the truss structural members 10 and 10.Between the bottom ends of the truss structural members 10 and the floorface 7 lower floor are disposed support shoes 6 a and 6 b, and betweenthe top ends of the truss structural members 10 and the beam member 8 aupper floor are disposed support shoes 6 c. The installing work of thetruss structural members 10 and 10 is easy because these members aremuch lighter in weight than the conventional stringers made of channelsteel or I-shaped steel.

Next, the truss structural members 10 and 10 are linked to each othervia the linking members 11, and the treads 12 are fixedly supported onthe tread supporting members 11 b of the linking members 11. The trussstructural members 10 and 10 can be linked to each other via the linkingmembers 11 just by press fitting one side of the linking end parts 11 aof the linking members 11 into the hubs 5 composing the upper chordmember 1 of the right-side truss structural member 10, and the otherside of the linking end parts 11 a of the linking members 11 into thehubs 5 composing the upper chord member 1 of the left-side trussstructural member 10, and then by applying later-described washers forpreventing pulling out. The linking members 11, of the right and lefttruss structural members 10, are set horizontal by being joined with thehubs 5 and 5 positioned at the same height. The treads 12, as shown inFIG. 5(a) and 5(b), are laid on the top faces of the tread supportingparts 11 b of the linking members 11, and are fixedly supported on thelinking members 11 with bolts or wooden screws which are inserted fromthe rear side of the tread supporting parts 11 b. Fixing the treads 12on the linking members 11 in advance facilitates the operation at abuilding site.

In addition, the handrail parts are assembled in advance. To be morespecific, as shown in FIG. 12 and FIG. 13(a), the linking end parts 13 aand 14 a on the upper side of the balusters 13 and 14 are press fit intothe linking grooves 15 b formed on the rail members 15 a of thehandrails 15 so as to join the handrails 15 and the balusters 13 and 14together. When the right and left rail members 15 a are each composed ofa single long-sized member, the linking end parts 13 a and 14 a on theupper side of the balusters 13 and 14 are inserted from an end part ofthe rail members 15 a and assembled.

Later, the linking end parts 13 a and 14 a on the bottom side of thebalusters 13 and 14 are press fit into the linking grooves 5 a of thehubs 5 so as to join the balusters 13 and 14 and the hubs 5 together.Since the linking end parts 13 have been cut at the coin angle α, thebalusters 13 are joined at an inclination of, degree from the axis ofthe hubs 5.

As shown in FIG. 11(b), on the top and bottom faces of the hubs 5 arefixed washers 5 d with bolts and nuts so as to prevent the frame members3, the lattice members 4, and the like from being pulled out in thedirection of the linking grooves 5 a, and then the bolts and nuts arecovered with ornamental caps 5 c.

As described hereinbefore, the staircase of the present embodimentenables the members to be joined with each other just by press fitting,which facilitates the assembly and reduces the number of components usedfor linking, thereby being economical. Furthermore, the truss structuralmembers 10, which look lighter in weight and have a sense of moreopenness than the conventional heavy members such as channel steel orI-shaped steel, creates no sense of oppression even if the staircase isinstalled indoors. In addition, no welding or special tools are requiredfor the joint between the members and the hubs 5, which provides high inworkability.

Since the linking members 11 are laid between the upper chord members 1and 1 of the truss structural members 10 and 10 and the treads 12 arefixedly supported on the top faces of the linking members 11, the trussstructural members 10 and 10 never protrude above the treads 12.Therefore, for example, when the staircase of the present embodiment isconstructed along a wall face, the wall face and the truss structuralmember 10 do not overlap each other above the treads 12, which canmaintain the appearance of the staircase.

In the right and left truss structural members 10 and 10, the upperchord members 1 and 1 are linked to each other via the linking members11, and as a result, the torsional rigidity of the staircase as a wholeand the flexural rigidity the side-to-side direction are improved, whichgreatly reduces the development of twisting or rolling of the staircasewhen people are going up and down the staircase.

Integrating the members into some units can further improve constructingefficiency. For example, when all the components (the truss structuralmembers 10 and 10, the linking members 11, the treads 12, the balusters13 and 14 and the handrails 15) are integrated into one unit, theconstructing of the staircase can be completed only by installing thisunit between the floor board 7 lower floor and the beam member 8 a upperfloor, which enables the staircase to be constructed in a short time. Itis also possible to assemble the truss structural members 10, thehandrails 15, and the balusters 13 and 14 beforehand.

Second Embodiment

The staircase according to a second embodiment of the present invention,as shown in FIG. 14 through FIG. 17, is composed of truss structuralmembers 20 and 20, which are a pair of right and left stringers; treads22 which are fixedly supported on the truss structural members 20;handrails 15 which are located above the side end parts of the treads22; and balusters l3 and l4 for supporting the handrails l5. Inaddition, in the present embodiment, as shown in FIG. 16, between thebottom ends of the truss structural members 20 and the floor face lowerfloor are disposed support shoes 23 a, and between the top ends of thetruss structural members 20 and the floor board 8 upper floor aredisposed support shoes 23 b.

The truss structural members 20, as shown in FIG. 15 and FIG. 16, areeach composed of an upper chord member 1 and a lower chord member 2which are inclined with the slope of the staircase, and a plurality oflattice members 4 for linking these chord members. In the presentembodiment, the upper chord member 1 and the lower chord member 2 areeach composed of a plurality of frame members 3 linked to each other viahubs 5, the lattice members 4 being composed of the same members as theframe members 3. Thus, the truss structural members 20 are each composedof the plurality of frame members 3 and the hubs 5 for linking them, theend parts of the frame members 3 being joined with the hubs 5 eacharranged at each node. Some of the lattice members 4 are laidhorizontally at the height of the risers (hereinafter referred to as thehorizontal lattice members 21).

The horizontal lattice members 21, as shown in FIG. 19, are eachcomposed of flat-shaped linking end parts 21 a and a tread supportingpart 21 b on which to fixedly support one of the treads 22, and laidhorizontally at the height of the risers (See FIG. 15). The linking endparts 21 a have the same cross sectional shape as the linking end parts3 a of the frame member 3 described in the first embodiment, but the tipparts of the linking end parts 21 a have the coin angle α because theaxis of the horizontal lattice members 21 is not orthogonal to the axisof the hubs 5. The horizontal lattice members 21 are extrusions ofaluminum alloy, and the linking end parts 21 a are formed by pressworking or the like. The portions to be pressed are cut beforehand inorder to prevent the tread supporting parts 21 b from hindering thepress working.

The treads 22, as shown in FIG. 18(a) and FIG. 18(b), are plate membersmade of wood or metal. In order to avoid contact with the upper chordmembers 1 and the lattice members 4, U-shaped cuttings are formed. Thetreads 22 are fixedly supported on the horizontal lattice members 21composing the truss structural members 20 with screws, nails or bolts,whereby the right and left side truss structural members 20 and 20 arelinked to each other via the treads 22.

The structures of the frame members 3, the lattice members 4, the hubs5, the balusters 13 and 14, and the handrails 15 and the method forjoining them will not be described in detail here because they are thesame as those described in the first embodiment.

The staircase according to the second embodiment also enables themembers to be joined together just by press fitting, which facilitatesthe assembly and reduces the number of components used for linking,thereby being economical. Furthermore, before the attachment of thetreads 22, a stack of truss structural members 20 can be carriedtogether, thereby providing high carrying efficiency.

When the staircase is viewed from the side, the treads are positionedbetween the upper chord members and the lower chord members, providing asimplified appearance. Furthermore, the truss structural members 20,which look lighter in weight and have a sense of more openness than theconventional heavy members such as channel steel or I-shaped steel,creates no sense of oppression even if the staircase is installedindoors.

Third Embodiment

The staircase according to a third embodiment of the present invention,as shown in FIG. 20, has curved truss structural members 30 and 30. Theother components are almost identical to the staircase according to thesecond embodiment.

The truss structural members 30 are each composed of an upper chordmember 31 and a lower chord member 32 which are inclined with the slopeof the staircase, and a plurality of lattice members 34 for linking thechord members together. In the present embodiment, the upper chordmember 31 and the lower chord member 32 are each composed of a pluralityof frame members 33 linked to each other via hubs 5, the lattice members34 being composed of the same members as the frame members 33. Thus, thetruss structural members 30 are each composed of the plurality of framemembers 33 and the hubs 5 for linking them, the end parts of the framemembers 33 being joined with the hubs 5 each arranged at each node. Someof the lattice members 34 are laid horizontally at the height of therisers (hereinafter referred to as the horizontal lattice members 35).

The frame members 33 have almost the same structure as the frame members3 described in the first and second embodiments; however, as shown inFIG. 21(b), the tips of the linking end parts 33 a of the frame members33 are bent at a necessary angle with respect to the axis of the framemembers 33 (hereinafter, bent angle β). The bent angle β is calculatedby the function of the curve shape, the truss shape, and the length ofthe frame members 33. Such a shape can be formed easily by press workingor the like.

As shown in FIG. 21(a), such frame members 33 can be sequentially linkedtogether via the hubs 5 to structure the curved truss structural members30.

A curved staircase can be easily constructed by composing the trussstructural members 30 from a plurality of frame members 33 and bendingthe linking end parts 33 a of the frame members 33 at a prescribedangle. To be more specific, in the conventional constructing of spiralstaircases or staircases having a curve when viewed in a plane, it hasbeen necessary to apply a bending process to the stringers made of I- orH-shaped steel, requiring a great deal of trouble and cost. On the otherhand, in the staircase according to the present embodiment, the framemembers 33 can be formed only by applying a simple process to the framemembers 3 shown in FIG. 6(a), and when it comes to hubs, the same hubs 5as those for straight staircases can be used, which is very economical.

Furthermore, the same structure and procedure can be used to constructstaircases in which the distance (the width of the treads 22) betweenthe truss structural members changes gradually like the truss structuralmembers 40 and 50 shown in FIG. 22(a) and FIG. 22(b), or unillustratedS-shaped staircases. As shown in FIG. 13(b), when each of the handrails15 has a joint, the joint piece 15 d is inserted inside the rail member15 a.

Fourth Embodiment

In the aforementioned embodiments, the upper chord members 1 and thelower chord members 2 are each formed by linking a plurality of framemembers 3; however, besides this, it is also possible to form the upperchord members and the lower chord members by using members long enoughto cover the whole length of the truss structural members.

In the staircase according to a fourth embodiment of the presentinvention, as shown in FIG. 23, the upper chord members 61 and the lowerchord members 62 composing the truss structural members 60 which arestringers are formed to be long enough to cover the whole length of thetruss structural members 60. In the same manner as each of theaforementioned embodiments, the truss structural members 60 are disposedright and left and linked to each other via the plurality of linkingmembers 65 on which the right and left upper chord members 61 and 61 arelaid horizontally at every riser height, and on the top faces of thelinking members 65 are fixedly supported the treads 66. In addition, inthe present embodiment, between the bottom ends of the truss structuralmembers 60 and the floor face 7 lower floor are disposed support shoes67 a and 67 b, and between the top end of the truss structural members60 and the beam member 8 a upper floor are disposed support shoes 67 c.

The truss structural members 60 are each composed of an upper chordmember 61, a lower chord member 62, hubs 64 (See FIG. 24) disposed ineach of the upper chord member 61 and the lower chord member 62, and aplurality of lattice members 63 for linking the upper and lower chordmembers 61 and 62.

The upper chord members 61 are made of aluminum alloy, and as shown inFIG. 25(b) and FIG. 25(c), are each shaped to have a groove part 61 fwhich extends in the direction of the slope of the staircase and whichis opened on the lattice member 63 side. To be more specific, the upperchord members 61 are extrusions each having a groove-shaped crosssection with an opened bottom face (a member having the groove part 61f), and on the top face inside the groove parts 61 f are formed tworidge portions 61 a extending in the longitudinal direction, and on thebottom of the side face inside the groove parts 61 f are formed ridgeportions 61 b extending in the longitudinal direction. On the bottomfaces of the upper chord members 61, as shown in FIG. 24, are providedlid members 61 c for covering the openings near the hubs 64, and lidmembers 61 for covering the openings on the other locations.

The lid members 61 c, as shown in FIG. 25(b), are fixed by burying theirside end parts into the grooves which have a U-shaped cross section andare formed by the inner face of the upper chord member 61 and the ridgeportions 61 b. The lid members 61 d, which have nearly the same shape asthe lid members 61 c as shown in FIG. 25(c), are provided with lockingpieces 61 e formed on their top faces in such a manner as to projectinto the upper chord members 61, and are fixed by locking the lockingpieces 61 e with the ridge portions 61 b of the upper chord members 61.Since the openings of the upper chord members 61 are closed by the lidmembers 61 c and 61 d, the appearance is improved. The lid members 61 calso serve to prevent the pulling out of the lattice members 63 joinedwith the hubs 64.

The lower chord members 62 are made of aluminum alloy, and as shown inFIG. 26(a) and FIG. 26(b), are each shaped to have a groove part 62 fwhich extends in the direction of the slope of the staircase and isopened on the lattice member 63 side. To be more specific, the lowerchord members 62 are extrusions having a groove-shaped cross sectionwith an opened top face (a member having the groove part 62 f) and areopen on the lattice member 63 side, and on the bottom face inside areformed two ridge portions 62 a extending in the longitudinal direction,and on the top of the side face inside are formed ridge portions 62 bextending in the longitudinal direction. On the top faces of the lowerchord members 62, as shown in FIG. 24, are provided lid members 62 c forcovering the openings near the hubs 64, and lid members 62 d forcovering the openings on the other locations.

The lid members 62 c and the lid members 62 d, as shown in FIG. 26(a)and FIG. 26(b), have the same structure as the lid members 61 c and thelid members 61 d shown in FIG. 25(b) and FIG. 25(c) to be installed inthe upper chord members 61. The lower cord members 62 have an opened topface which can be closed by the lid members 62 c and 62 d to preventdust accumulation inside.

The lattice members 63, like the lattice members 4 shown in FIG. 6(b)are tubular members having flat-shaped linking end parts 63 a at bothends (See FIG. 24), the linking end parts 63 a having notches at theirtips (See FIG. 25(a)). In the lattice members 63, the tips of thelinking end parts 63 a have been cut at the angle α(hereinafter referredto as the coin angle α) in the same manner as in the lattice members 4shown in FIG. 6(c). The lattice members 63 are extrusions of aluminumalloy, and the linking end parts 63 a are formed by press working or thelike. Since they are long flattened in the axial direction of the hubs64, the linking end parts 63 a have a joint structure strong against theexternal force in the axial direction of the hubs 64.

The hubs 64, as shown in FIG. 25(a) and FIG. 25(b), are column-shapedand each have a bolt insertion hole 64 c in the center. On the outersurfaces of the hubs 64 are carved linking grooves 64 a along the axialdirection of the hubs 64. The linking grooves 64 a have the same crosssectional shape as the tip parts of the linking end parts 63 a of thelattice members 63, and their inner walls are provided with notcheswhich are formed to be engaged with the notches of the linking end parts63 a. The hubs 64 are shaped to have an oval cross section and areburied between the ridge portions 61 a and 61 a on the top faces andbetween the ridge portions 61 b and 61 b on the side faces of the upperchord members 61. The hubs 64 are installed in the lower chord members62 in the same manner. Covering the head parts of bolts B penetratingthe hubs 64 and nuts N with semispherical caps 64 b improves theappearance.

The hubs 64 are installed inside the upper chord members 61 and thelower chord members 62 at intervals of the riser height, and the linkingend parts 63 a of the lattice members 63 are press fit into the linkinggrooves 64 a of the hubs 64 so as to join the lattice members 63 and thehubs 64, thereby constructing the truss structural members 60. At thistime, as shown in FIG. 25(a), the notches formed on each of the linkinggrooves 64 a and the linking end parts 63 a are engaged with each other,which prevents the lattice members 63 from being pulled out in the axialdirection.

The lattice members 63 are joined with the linking grooves 64 a at aninclination of the coin angle α because the linking end parts 63 a ofthe lattice members 63 have an inclination of the coin angle α at theirtips.

The linking members 65, as shown in FIG. 24, are hollow members having apolygonal cross section and are each composed of an inclined face(hereinafter referred to as the attachment face 65 b) which is inclinedwith the slope of the staircase to come into contact with the top faceof the upper chord member 61; and a horizontal face on which one of thetreads 66 is placed (hereinafter referred to as the tread supportingface 65 a). And the linking members 65 are fixed on the upper chordmembers 61 in cooperation with the hubs 64 via the bolts B inserted intothe bolt insertion holes 64 c of the hubs 64 from inside the linkingmembers 65. The vertically adjacent linking members 65 (the treadmounting faces 65 a) are arranged at intervals of the riser height.

The treads 66 are plate members made of wood or metal, and are fixed onthe tread supporting faces 65 a of the linking members 65 with screws,nails, or bolts as shown in FIG. 27.

The following is a description of the constructing process of thestaircase according to the fourth embodiment. In the followingdescription, the aforementioned members are assembled in sequence at abuilding site of the staircase; however, instead of this, it is alsopossible to assemble some units of members integrated in considerationof efficiency in carrying and constructing.

First, the truss structural members 60 are laid between the floor board7 lower floor and the beam member 8 a upper floor with a prescribeddistance between the truss structural members 60. As shown in FIG. 23,between the bottom ends of the truss structural members 60 and the floorface 7 lower floor are disposed support shoes 67 a and 67 b, and betweenthe top ends of the truss structural members 60 and the beam member 8 aupper floor are disposed support shoes 67 c. The installing work of thetruss structural members 60 and 60 is easy because these members aremuch lighter in weight than the conventional stringers made of channelsteel or I-shaped steel.

Next, the truss structural members 60 and 60 are linked to each other byfixing the linking members 65 on the top faces of the upper chordmembers 61. The linking members 65, as shown in FIG. 24, are installedto the hubs 64 so as to be fixed on the top faces of the upper chordmembers 61 with bolts B inserted into the bolt insertion holes 64 c ofthe hubs 64 from inside the linking members 65.

Then, the treads 66 are fixedly supported on the tread supporting faces65 a of the linking members 65. Fixing the treads 66 on the linkingmembers 65 in advance facilitates the operation at a building site.

Furthermore, the balusters 13 and 14 are installed on the upper chordmembers 61 and the treads 66, and then the handrails 15 are attached tothe top ends of the balusters 13 and 14 so as to complete theconstructing of the staircase. Fixing the balusters 13 and 14 to thehandrails 15 in advance can reduce the constructing time at a buildingsite.

Similar to the staircases of the above embodiments, the staircaseaccording to the fourth embodiment enables the members to be easilyintegrated into units. And the truss structural members 60, which looklighter in weight and have a sense of more openness than theconventional heavy members such as channel steel or I-shaped steel,creates no sense of oppression even if the staircase is installedindoors. Furthermore, the hubs 64 are installed inside the upper chordmembers 61 and the lower chord members 62, providing a simplifiedappearance.

In the fourth embodiment, the treads 66 are fixedly supported on the topfaces of the linking members 65; however, as shown in FIG. 28, it isalso possible to place block-shaped supporting members 68 and 68 havingthe same cross sectional shape as the linking members 65 on the topfaces of the right and left upper chord members 61 and 61, and to placethe treads 66 on the top faces of the supporting members 68 and 68. Inthis case, the right and left pair truss structural members 60 and 60are linked to each other via the treads 66. This allows the trussstructural members 60 to be carried in a stacked condition, whichprovides high carrying efficiency.

The upper chord members 61 are not restricted to the one shown in FIG.25(b), and for example like the upper chord members 61′ shown in FIG.29(a), can be each composed of a groove part 61 f having an openedbottom face and a hollow part 61 g. The provision of the hollow parts 61g beside the groove parts 61 f can improve the rigidity of the upperchord members 61′, thereby forming a cross sectional structure strongagainst the vertical load and axial compression applied to the upperchord members 61. In this case, the hubs 64 are installed inside thegroove parts 61 f.

In the same manner, the lower chord members 62 are not restricted to theone shown in FIG. 26(a), and for example like the lower chord members62′ shown in FIG. 29(b), can be each composed of a groove part 62 fhaving an opened top face and a hollow part 62 g. The provision of thehollow parts 62 g beside the groove parts 62 f can improve the rigidityof the lower chord members 62′. In this case, the hubs 64 are installedinside the groove parts 62 f.

Forming the truss structural members 60 by the upper chord members 61′and the lower chord members 62′ can greatly reduce the development ofvertical flexure, twisting or rolling of the staircase when people aregoing up and down the staircase.

In the present embodiment, both the upper chord members 61 and the lowerchord members 62 are made long enough to cover the whole length of thetruss structural members 60; however, it is also possible to make one ofthem long enough to cover the whole length of the truss structuralmembers 60 and to compose the other by short-sized frame members linkedvia node members (hubs) as shown in the second embodiment.

Fifth Embodiment

In the fourth embodiment, the upper chord members 61 and the lower chordmembers 62 are each composed of members having a groove part, and thehubs 64 are installed inside the groove parts; however, like thestaircase according to a fifth embodiment shown in FIG. 30 and FIG. 31,it is also possible to compose each of the upper chord members 71 andthe lower chord members 72 by hollow members and to install the hubs 73on the bottom faces of the upper chord members 71 and on the top facesof the lower chord members 72. FIG. 30 is a cross section view takenalong the line Y4-Y4 of FIG. 31.

In the staircase according to the fifth embodiment, the upper chordmembers 71 and the lower chord members 72 composing the truss structuralmembers 70 are each composed of a single long-sized member having alength to cover the whole length of the truss structural members 70, andhubs 73 are installed on the bottom faces of the upper chord members 71and on the top faces of the lower chord members 72. In addition, on thetop faces of the upper chord members 71 are provided linking members 65,and in the present embodiment, the hubs 73, the upper chord members 71,and the linking members 65 are fixed integrally.

The upper chord members 71, in the present embodiment, are hollowextrusions of aluminum alloy, and as shown in FIG. 30, have arectangular cross section. Inside the upper chord members 71 are formedseparating boards 71 a and 71 a in the vertical direction. The upperchord members 71 are very lightweight because of being hollow inside,and the presence of the separating boards 71 a and 71 a inside providesa cross sectional structure strong against the vertical load and axialcompression applied to the upper chord members 71.

The lower chord members 72, in the present embodiment, are hollowextrusions of aluminum alloy, and have the same cross sectional shape asthe upper chord members 71, although their illustration is omitted. Theother structures will not be described in detail here because they arethe same as those in the staircase of the fourth embodiment.

When the hubs 73 are installed on the bottom faces of the upper chordmembers 71, as shown in FIG. 30, bolts B are inserted from the bottomfaces of the hubs 73 through the upper chord members 71 up to the insideof the linking members 65, and fastened with nuts N. Although it is notillustrated, when the hubs 73 are installed on the top faces of thelower chord members 72, bolts can be inserted from the top faces of thehubs 73 to the bottom faces of the lower chord members 72, and befastened with nuts.

Thus, when the hubs 73 are installed on the bottom faces of the upperchord members 71 and the top faces of the lower chord members 72, theinner shapes of the upper chord members 71 and the lower chord members72 can be determined in accordance with the load and other requirements.

In the present embodiment, both the upper chord members 71 and the lowerchord members 72 are made long enough to cover the whole length of thetruss structural members 70; however, it is also possible to make one ofthem long enough to cover the whole length of the truss structuralmembers 70 and to compose the other by short-sized frame members linkedvia node members (hubs) as shown in the second embodiment.

Sixth Embodiment

The staircase according to a sixth embodiment of the present invention,as shown in FIG. 32 through FIG. 36, is composed of truss structuralmembers 80 and 80 which are a pair of right and left stringers; aplurality of linking members 83 for linking the stringers; treads 66which are fixedly supported on the linking members 83; handrails 15which are located above the side end parts of the treads 66; andbalusters 13 for supporting the handrails 15. In the present embodiment,as shown in FIG. 32, between the bottom ends of the truss structuralmembers 80 and the floor face 7 lower floor are disposed support shoes85 a and 85 b, and between the top ends of the truss structural members80 and the beam member 8 a upper floor are disposed support shoes 85 c.

The truss structural members 80, as shown in FIG. 32 and FIG. 33, areeach composed of an upper chord member 1 and a lower chord member 2which are inclined with the slope of the staircase; and a plurality oflattice members 4 for linking them. The upper chord member 1 and thelower chord member 2 are each composed of a plurality of frame members 3linked to each other via hubs 5. Along the upper chord members 1 areprovided upper reinforcing members 81, and along the lower chord members2 are provided lower reinforcing members 82.

The structures of the frame members 3, the lattice members 4, the hubs5, the balusters 13, and the handrails 15 and the method for joiningthem will not be described in detail here because they are the same asthose described in the first embodiment.

The upper reinforcing members 81 are extrusions of aluminum alloy, andas shown in FIG. 32, have the same length as the whole length of theupper chord members 1. As shown in FIG. 34(a), the cross sectional shapeof the upper reinforcing members 81 is groove shaped having an openedbottom face so as to include the upper chord members 1 (See FIG. 33). Tobe more specific, the upper reinforcing members 81 are each composed ofa top plate 81 a located on the top face side of the upper chord members1, and side plates 81 b and 81 b extending downwards from the side endparts of the top plates 81 a so as to cover the upper chord members 1(frame members 3), the top plates 81 a being in contact with the topfaces of the hubs 5.

The lower reinforcing members 82 are flat-shaped plate members made ofaluminum alloy, and in the present embodiment, as shown in FIG. 32, havethe same length as the portions of the lower chord members 2 that are inparallel with the upper chord members 1.

The linking members 83 are hollow extrusions of aluminum alloy having apolygonal cross section, and are each composed of an inclined face(hereinafter referred to as the attachment face 83 b) which is inclinedwith the slope of the staircase and which is in contact with the topface of the upper reinforcing member 81, and a horizontal face on whichthe one of the treads 66 is placed (hereinafter referred to as the treadplacing face 83 a), and are each fixed on the top face of the upperreinforcing member 81 in the hub 5 area. In other words, the linkingmembers 83 are laid between the right and left upper chord members 1 and1 which are linked to each other via the linking members 83. As shown inFIG. 34(b), on the top faces inside the linking members 83 are formednut pockets 83 c for accommodating the nuts to fix the treads 66, and onthe top faces and side faces inside the linking members 83 are formedscrew pockets 83 d. Into the screw pockets 83 d are screwed forinstalling cap plates 84 (See FIG. 33) for covering the openings of theend faces of the linking members 83. The nut pockets 83 c and the screwpockets 83 d are formed when the linking members are extruded.

The upper reinforcing members 81 can be fixed to the hubs by coveringthe upper reinforcing members 81 from the top of the upper chord members1 (See FIG. 35(a) and FIG. 35(b)); disposing the linking members 83 onthe top faces of the upper reinforcing members 81 (See FIG. 36); andinserting the bolts from the bottom faces of the hubs 5 to penetrate theupper reinforcing members 81 up to inside the linking members 83, andfixing them with the nuts. At this time, the linking members 83 arefixedly supported on the top faces of the upper reinforcing members 81.The lower reinforcing members 82 are fixed by screwing bolts which havebeen penetrated up to the top faces of the hubs 5 from their lower sidewith the nuts. Furthermore, the lower reinforcing members 82 come intocontact with the bottom faces of the hubs 5 composing the lower chordmembers 2 so as to prevent the pulling out of the frame members 3 andthe lattice members 4 in the downward direction.

Thus integrating the plurality of hubs 5 composing the upper chordmembers 1 with the upper reinforcing members 81 can improve the flexuralrigidity of the truss structural members 80 in the out-of-planedirection, thereby greatly reducing the development of rolling whenpeople are going up and down the staircase. When the staircase is viewedfrom the side, the upper chord members 1 are covered with the sideplates 81 b of the upper reinforcing members 81, which provides asimplified appearance.

The truss structural members of each of the aforementioned embodimentshave high rigidity against the load in the in-plane direction (verticaldirection), but have comparatively low rigidity against the load in theout-of-plane direction (side-to-side direction). For this reason, in astaircase with supplementary means such as stringers, the right and lefttruss structural members composing the stringers are linked to eachother via linking members or the treads to improve the rigidity againstthe out-of-plane direction. However, the truss structural members 80according to the present embodiment have improved rigidity in theout-of-plane direction, which enables the linking members 83 to becomposed of lighter weight members.

The cross sectional shapes of the upper reinforcing members 81 and thelower reinforcing members 82 are not restricted to the one shown in FIG.34(a) and can be L-shaped as shown in FIG. 37(a), for example. Byshaping the upper reinforcing members 81 and the lower reinforcingmembers 82 like the letter L or a groove, the frame members 3 composingthe upper chord members 1 or the lower chord members 2 are concealed,making the design simple and also improving the rigidity in the verticaldirection. When the upper reinforcing members 81 or the lowerreinforcing members 82 are flat-shaped, there are clearances betweenthese reinforcing members and the frame members 3; however, in the caseof the L- or groove-shaped members, the clearances can be hidden,thereby improving the design.

As shown in FIG. 37(b), the upper reinforcing members 81 can beexclusively disposed without using the lower reinforcing members 82. Inthis case, the right and left lower chord members 2 and 2 can be linkedto each other via the linking frame members 9. Although it is notillustrated, the lower reinforcing members 82 can be exclusivelydisposed without using the upper reinforcing members 81.

Although it is not illustrated, the truss structural members having thesame structure as the aforementioned truss structural members 80 can beutilized as various structural members including architecturalstructural members, beside the stringers of staircases. To be morespecific, in the truss structural members in which the upper and lowerchord members are each composed of a plurality of frame members linkedto each other via hubs, disposing reinforcing members along the chordmembers and fixing each of the reinforcing members to at least threehubs can integrate the plurality of hubs composing the chord memberswith the reinforcing members, whereby at least the intermediate hubs arereinforced in the direction that rotates the hubs. This improves theflexural rigidity of the truss structural members in the out-of-planedirection, and reduces deformation in the out-of-plane direction.Furthermore, the use of the reinforcing members extending across thewhole length of the chord members as in the present embodiment canprovide reinforcement throughout the length.

Therefore, for example, when a plurality of truss structural members areused together, the members to link adjacent truss structural members canbe omitted or made lighter in weight, thereby providing a simplifiedappearance. This can be applied to the truss structural members providedwith so-called ball joint type nodes, besides the truss structuralmembers utilizing hubs as in the present embodiment.

Seventh Embodiment

The staircase according to a seventh embodiment of the presentinvention, as shown in FIG. 38, has an intermediate reinforcing member91 fixedly provided on the bottom faces of the plurality of linkingmembers 83 for linking the truss structural members 90 and 90 which area pair of right and left stringers. To be more specific, the pluralityof linking members 83 adjacent in the height direction are integrated bybeing linked to each other via the intermediate reinforcing member 91.

The intermediate reinforcing member 91 is a flat-shaped plate membermade of aluminum alloy, and is preferably long enough to integrate thelinking members 83 from the lowermost through the uppermost. Theintermediate reinforcing member 91 is fixed by contacting its top facewith the attachment faces 83 b of the linking members 83 (See FIG.34(b)) and screwing drill screws from the bottom face side. Theintermediate reinforcing member 91 can be a synthetic resin plate suchas a polycarbonate plate or an acrylic resin plate, instead of theflat-shaped aluminum alloy plate.

Thus integrating the plurality of linking members 83 with theintermediate reinforcing member 91 having a flat shape and high strengththe side-to-side direction makes it possible that when the load theside-to-side direction is applied to one of the linking members 83(treads 66), the load is received by the intermediate reinforcing member91 without being totally transferred to the truss structural members 90which are the stringers, and is then dispersed to the other linkingmembers 83. This greatly reduces the development of twisting or rollingwhen people are going up and down the staircase, and makes the linkingmembers 83 lighter in weight.

Eighth Embodiment

The staircase according to an eighth embodiment of the presentinvention, as shown in FIG. 39, has a board member 96 between a pair ofright and left truss structural members 95 and 95.

The board member 96, in the present embodiment, is a board member havinga number of small holes, and is fixed on the top faces of the pluralityof hubs 5 composing the upper chord members 1. The board member 96 couldalso be a polycarbonate board, an acrylic resin board, an aluminum alloyboard, or the like.

Thus providing the board member 96 between the right and left upperchord members 1 and 1 can integrate the right and left truss structuralmembers 95 and 95, and reduce shearing deformation on the plane formedby the upper chord members 1 and 1, thereby greatly reducing thedevelopment of twisting or rolling when people are going up and down thestaircase.

The board member 96 can be applied either across the whole length of theupper chord members 1 or a part of it. For example, as shown in FIG. 40,fixing a board member 96′ onto adjacent two hubs 5 on the right and onthe left (four in total) can reduce shearing deformation on the planeformed by the four hubs 5, thereby greatly reducing the development oftwisting or rolling when people are going up and down the staircase.

In the staircase shown in FIG. 39, the board member 96 is disposedbetween the right and left upper chord members 1 and 1; however, insteadof this, it can be disposed between the right and left lower chordmembers 2 and 2, or both between the upper chord members 1 and 1 andbetween the lower chord members 2 and 2.

The truss structural members illustrated in the first to seventhembodiments are all single Warren trusses; however, instead of this,they can be Pratt trusses or Howe trusses.

The node members, which are column-shaped hubs 5 in the presentembodiment, can be square column-shaped or other shaped, or have aball-joint type node structure. Furthermore, the lattice members and theframe members can be joined by bolts or welding.

Ninth Embodiment

As shown in FIG. 41, the staircase according to this embodimentcomprises, as main parts, a pair of right and left truss structuralmembers 100 and 100 inclining with the slope of the staircase, and aplurality of treads 160 disposed between the truss structural members100 and 100. Between treads 160 and 160 adjacent to each other, a riser165 is attached. In FIG. 41, the handrails are omitted.

The truss structural member 100 is, as shown in FIG. 42, a so-calledwarren truss, comprising an upper chord member 110 and a lower chordmember 120 inclining with the slope of the staircase, and a plurality oflattice members 130 linking the upper chord member 110 and the lowerchord member 120 to each other. In this embodiment, the upper chordmember 110 and the lower chord member 120 are inclined by 45 degrees,and the lattice members 130 are set so as to be inclined by 45 degreeswith respect to the upper chord member 110 and the lower chord member120. Therefore, in this embodiment, the horizontal lattice members 130and the vertical lattice members 130 are disposed alternately. The slopeof the staircase is not limited to 45 degrees, and as a matter ofcourse, it is appropriately changeable according to installationconditions.

Furthermore, in this embodiment, support shoes 140 and 140 areinterposed between the truss structural members 100 and the buildingskeleton K, and likewise, support shoes 140 and 140 are also interposedbetween the upper ends of the truss structural members 100 and thebuilding skeleton K.

The upper chord member 110 has, as shown in FIG. 43(a) a plurality ofcolumn-shaped upper node members (hereinafter, referred to as upper hubs111) provided in range with each other at predetermined intervals in thedirection of the staircase inclination, upper frame members 112 that areshort in length and provided between the upper hubs 111 and 111 adjacentin the direction of the staircase inclination, and an upper throughmember 113 having a long length. Namely, the upper chord member 110comprises one long-length upper through member 113, a plurality ofshort-length frame members 112 provided in series along the upperthrough member 113, and upper hubs 111 that link the upper frame members112 adjacent to each other in the direction of the staircaseinclination.

The lower chord member 120 has, as shown in FIG. 43(a) a plurality ofcolumn-shaped lower node members (hereinafter, referred to as lower hubs121) provided in series in the direction of the staircase inclination,short-length lower frame members 122 disposed between the lower hubs 121and 121 adjacent to each other in the direction of the staircaseinclination, and a long-length lower through member 123. Namely, thelower chord member 120 comprises one long-length lower through member123, a plurality of short-length lower frame members 122 linked alongthe lower through member 123, and lower hubs 121 which link the lowerframe members 122 adjacent to each other in the direction of thestaircase inclination.

In this embodiment, the difference in height between the upper hubs 111and 111 adjacent to each other in the direction of the staircaseinclination and the difference in height between the lower hubs 121 and121 adjacent to each other in the direction of the staircase inclinationare the heights of the risers. As shown in FIG. 43(a), the upper hub 111and the lower hub 121 adjacent to each other in the cross direction ofthe staircase are disposed at the same height.

The upper hub 111 is, as shown in FIG. 44(a), a short column with acircular cross section formed of an aluminum alloy-made extruded member.On the outer circumferential face of the upper hub 111, five linkinggrooves 111 a are formed to be concave along the axis C1 of the upperhub 111, and at the center of the upper hub 111, a bolt insertion hole111 b is formed along the axis C1. The width of the upper hub 111 is thesame as that of the linking end part 112 a of the upper frame member 112described later.

The linking grooves 111 a of the upper hub 111 are formed radiallyaround the bolt insertion hole 111 b, and the central angle of theadjacent linking grooves 111 a and 11 a is 45 degrees. Furthermore, onthe inner walls of the linking grooves 111 a, notches are formed. Thelinking grooves 111 a and the bolt insertion hole 111 b are formed whenthe aluminum alloy is extruded. The form of the upper hub 111 and thenumber and the arrangement of linking grooves 111 a are not limited tothose of this embodiment, and are changeable as appropriate according tothe slope of the staircase.

Furthermore, the upper hub 111 is disposed so that, as shown in FIG.43(b), the axis C thereof is orthogonal to the truss plane T (planeformed by the upper chord member 110 and the lower chord member 120) ofthe truss structural member 100, as a result, the linking grooves 111 aand the bolt insertion hole 111 b (see FIG. 44(a)) of the upper hub 111are orthogonal to the axis of the upper chord member 110 and the axis ofthe lattice members 130. For example, in the side view shown in FIG.43(a), the axis C1 of the upper hub 111 becomes vertical to the surfaceof the document paper.

Furthermore, as shown in FIG. 45, in the linking grooves to which theupper frame member 112 are not linked among the linking grooves 111 a,groove filling members 111 f having the same dimensions and shapes asthose of the linking grooves 111 a are fitted (inserted) for the purposeof improvement in appearance and prevention of accumulation of dust.

Detailed description of the lower hubs 121 is omitted since they havethe same structure as that of the upper hubs 111 (see FIG. 44(a) andFIG. 44(b)).

The upper frame member 112 is formed by processing a hollow extrudedmember with a circular cross section made of an aluminum alloy, and asshown in FIG. 46(a), on both ends thereof, flat-shaped linking end parts112 a are provided. The linking end parts 112 a are formed by pressingboth ends of the hollow extruded member flat by a pressing machine, etc.

The linking end parts 112 a of the upper frame members 112 can be fittedinto the linking grooves 111 a (see FIG. 44(a)) of the upper hubs 111,and as shown in FIG. 46(b), at their tip ends, notches to be engagedwith the notches of the inner walls of the linking grooves 111 a areformed in the direction orthogonal to the axis C2. The tip ends of thelinking end parts 112 a are cut along the direction orthogonal to theaxis C2.

To link the upper frame members 112 to the upper hubs 111, as shown inFIG. 44(a), the linking end parts 112 a of the upper frame members 112are fitted (inserted) into the linking grooves 111 a from the end faceside of the upper hubs 111. This work does not require welding orspecial tools, there by providing high workability. Furthermore, inorder to fill in the fine clearances created between the linking grooves111 a and the linking end parts 112 a, it is also possible to pour glueor the like into the linking grooves 111 a.

When the linking end parts 112 a of the upper frame members 112 arefitted into the linking grooves 111 a of the upper hubs 111, as shown inFIG. 45, notches formed on the linking grooves 111 a and the linking endparts 112 a are engaged with each other, which prevents the upper framemembers 112 from being pulled out in the axis direction.

In addition, as shown in FIG. 46(b), since the linking end parts 112 aof the upper frame members 112 are orthogonal to the axis C2, when thelinking end parts 112 a are fitted into the linking grooves 111 a (seeFIG. 44(a)) of the upper hub 111, the axis C2 of the upper frame members112 and the axis C1 of the upper hubs 111 are orthogonal to each other.Furthermore, since the linking end parts 112 a are formed to be flat andlong in the direction of the axis C1 of the upper hub 111, a jointstructure strong in strength against the external force in the directionof the axis C1 of the upper hub 111, that is, the external force in theside-to-side direction of the staircase is formed.

Detailed description of the lower frame members 122 is omitted sincetheir structure is the same as that of the upper frame members 112 (seeFIG. 46(a) and FIG. 46(b)).

Since the upper hubs 111 and the lower hubs 121 are disposed so that theaxes C1 thereof are orthogonal to the truss planes T (see FIG. 43(b)),so that even in a case where the staircase has a slope different fromthat of this embodiment, the linking grooves 111 a of the upper hubs 111and the linking grooves 121 a of the lower hubs 121 (see FIG. 44) alwaysare orthogonal to the axes of the upper frame members 112 and the lowerframe members 122. Namely, both ends of the upper frame members 112 andthe lower frame members 122 are cut along the direction orthogonal tothe axes thereof regardless of the slope of the staircase (see FIG.46(b)), and since it is not necessary to change the angles of both endsof the upper frame members 112 and the lower frame members 122 accordingto the slope of the staircase, the staircase becomes suitable for massproduction and high in productivity.

The upper through member 113 is an extruded member made of an aluminumalloy, and in this embodiment, its length is from the upper end to thelower end of the upper chord members 110 (see FIG. 42). In addition, asshown in FIG. 47(b), the upper through member 113 has a groove shape thebottom face of which opens, which can house the upper hubs 111 and theupper frame members 112. In greater detail, the upper through member 113is composed of a pair of right and left side plates 113 a and 113 a tocome into contact with both side end faces of the upper hubs 111, and anupper plate 113 b that links the upper ends of the side plates 113 a and113 a.

In addition, as shown in FIG. 47(a) and FIG. 47(b), the upper throughmember 113 is fixed to the side end faces of the upper hubs 111. To fixthe upper through member 113 to the upper hubs 111, the upper throughmember 113 is covered on the upper hubs 111 from above (see FIG. 49),bolts B11 are inserted into the bolt insertion holes 111 b (see FIG.44(a)) of the upper hubs 111 from the side plate 113 a side of the upperthrough member 113, and the bolts B11 projecting to the side plates 113a on the opposite side are fastened by nuts N11. To the bolts B11 andnuts N11 projecting out of the upper through member 113, cap members 181for improvement in appearance are attached.

The lower through member 123 is an extruded member made of an aluminumalloy, and in this embodiment, its length is from the upper end to thelower end of the lower chord member 120 (see FIG. 42). In greaterdetail, as shown in FIG. 47(b), the lower through member 123 is composedof a side plate 123 a that comes into contact with the side end faces ofthe inner side of the lower hubs 121, and a lower plate 123 b projectingdownward below the lower hubs 121 from the lower end of the side plate123 a, and has an L-shaped cross section.

Furthermore, as shown in FIG. 47(a) and FIG. 47(b), the lower throughmember 123 is fixed to the side end faces of the inner sides of thelower hubs 121. To fix the lower through member 123 to the lower hubs121, the lower plate 123 b is positioned below the lower hubs 121 whilethe side plate 123 a is made to contact with the inner side faces of thelower hubs 121, bolts B11 are inserted into the bolt insertion holes 121b (see FIG. 44(b)) of the lower hubs 121 from the side of the side plate123 a of the lower through member 123, and the bolts B11 projecting tothe side end faces on the outsides of the lower hubs 121 are fastened bynuts N11. To the bolts B11 and the nuts N11 projecting from the lowerhubs 121, cap members 181 for improvement in appearance are attached.

The shapes of the upper through member 113 and the lower through member123 are not limited to those illustrated as long as they can be attachedto the side end faces of the upper hubs 111 and the side end faces ofthe lower hubs 121, and for example, the shapes may be flat althoughtheir illustration is omitted.

The lattice member 130 is formed by processing hollow extruded memberswith a circular cross section made of an aluminum alloy, which is thesame type member as that of the upper frame member 112 shown in FIG.46(a). Namely, the lattice member 130 has, on its both ends, flat-shapedlinking end parts 130 a (see FIG. 45) that can be fitted into thelinking grooves 111 a of the upper hubs 111 and the linking grooves 121a of the lower hubs 121 (see FIG. 44), and on their tip ends, notches tobe engaged with the notches on the inner walls of the linking grooves111 a are formed in the direction orthogonal to the axis. Furthermore,in the same manner as in the upper frame members 112 shown in FIG.46(a), both ends of the lattice member 130 are cut along the directionorthogonal to its axis. Therefore, when the linking end parts 130 a ofthe lattice members 130 are fitted into the linking grooves 111 a of theupper hubs 111 or the linking grooves 121 a of the lower hubs 121 (seeFIG. 44) the axes of the lattice members 130 and the axes of the hubs111 and 121 are orthogonal to each other.

Since the upper hubs 111 and the lower hubs 121 are disposed so thattheir axes C1 are orthogonal to the truss planes T (see FIG. 43(b)),even in a case where the staircase has a slope different from that ofthis embodiment, the linking grooves 111 a of the upper hubs 111 and thelinking grooves 121 a of the lower hubs 121 always are orthogonal to theaxes of the lattice members 130. Namely, both ends of the latticemembers 130 are cut along the direction orthogonal to their axesregardless of the slope of the staircase, and since it is not necessaryto change the angles of the end parts of the lattice members 130according to the slope of the staircase, the staircase becomes suitablefor mass production and high in productivity.

The support shoes 140 are formed of extruded members made of an aluminumalloy, and as shown in FIG. 48(a), FIG. 48(b), and FIG. 48(c), each havea base plate 141 to come into contact with the building skeleton K, anda pair of projecting plates 142 and 142 projecting from this base plate141. The space between the projecting plates 142 and 142 is set so as toenable the upper chord member 110 or the lower chord member 120 to beinserted inside as shown in FIG. 48(b) and FIG. 48(c), and is equal tothe width of the upper through member 113.

To attach the support shoes 140 to the upper and lower ends of the upperchord member 110, as shown in FIG. 48(b), the end part of the upperchord member 110 is inserted between the projecting plates 142 and 142of the support shoe 140, and bolt insertion holes (not shown) formed inthe projecting plates 142 and the bolt insertion holes 111 b of theupper hubs 111 are aligned with each other (see FIG. 44(a)), andthereafter, the bolt B13 is inserted from the side of one of theprojecting plates 142 and the bolt B13 projecting from the otherprojecting plate 142 is fastened by a nut N13. The method for attachingthe support shoes 140 to the upper and lower ends of the lower chordmember 120 is the same, and in this case, a spacer 158 is interposedbetween the projecting plates 142 of the support shoe 140 and the sideend face of the lower hub 121 (see FIG. 48(c)).

In this embodiment, as shown in FIG. 47 and FIG. 50, tread receivingmembers 150 for attaching the treads 160 to the side faces of the upperchord member 110 and the lower chord member 120 are provided side byside at predetermined intervals.

The tread receiving member 150 comprises, as shown in FIG. 47(a) andFIG. 47(b), a fixed plate 151 that comes into contact with the side face(side plate 113 a) of the upper through member 113 or the side face(side plate 123 a) of the lower through member 123 and a supportingplate 152 that projects inward from the upper end of the fixed plate151, and has an L-shaped section.

When the upper hubs 111 and the upper through member 113 are fixed, thetread receiving members 150 of the upper chord member 110 are actuallyattached together. In greater detail, when the upper hub 111 and theupper through member 113 are fixed, the fixed plate 151 of the treadreceiving members 150 is made to contact with the side plate 113 a ofthe upper through member 113 and fastened to the upper hub 111 togetherwith the upper through member 113 by a bolt B1 and a nut N11 (see FIG.47(a) and FIG. 47(b)). Namely, the tread receiving members 150 are fixedto the side end faces of the upper hubs 111 together with the upperthrough member 113. Likewise, the tread receiving members 150 of thelower chord member 120 side are fixed to the side end faces of the lowerhubs 121 together with the lower through member 123.

In this embodiment, the tread 160 comprises, as shown in FIG. 50, aplate member 161 that is rectangular in its plan view and joint members162 and 162 attached to both side end parts of the plate member 161.

As a material of the plate member 161, any material such as wood ormetal can be used as long as it has a quality and structure withrigidity and strength that withstands for a bending moment developing atits center due to a vertical load.

The joint member 162 is formed of an extruded member made of an aluminumalloy, and comprises, as shown in FIG. 47(b), a side contact plate 162 ato come into contact with the side end face of the plate member 161, alower contact plate 162 b that projects along the back face of the platemember 161 from the lower end of this side contact plate 162 a, and aprojecting plate 162 c that projects horizontally outward from the sideface of the side contact plate 162 a. The length of the joint member 162is determined so as to be across the tread receiving member 150 attachedto the upper hub 111 and the tread receiving member 150 attached to thelower hub 121 adjacent horizontally to the upper hub 111. The jointmember 162 is fixed to the plate member 161 by driving drill screws notshown from the lower contact plate 162 b.

To attach the treads 160 to the truss structural members 100, as shownin FIG. 47(a) and FIG. 47(b), the projecting plates 162 c of the jointmembers 162 are placed on the top faces of the supporting plates 152 ofthe tread receiving members 150, and the supporting plates 152 and theprojecting plates 162 c are fixed by bolts B12 and nuts N12.

The handrails (copings) 171 and balusters 172 supporting the handrails171 are not limited to those shown in FIG. 42. Namely, the handrails 171and balusters 172 are not structures that support the staircase itself,so that various forms, designs, and materials can be freely selected forthem.

The balusters 172 are attached by using the upper hubs 111 and the lowerhubs 121. Attachment by using the side plate 123 a of the lower throughmember 123 (see FIG. 47(b)) is also possible.

Procedures for constructing the staircase according to this embodimentare described with reference to FIG. 42 through FIG. 45 and FIG. 49through FIG. 50.

To construct the staircase according to this embodiment, as shown inFIG. 50, two truss structural members 100 formed into a unit areattached in advance to the building skeleton K interspatially, treads160 are attached between the right and left truss structural members 100and 100, and furthermore, the balusters 172 and the handrails 171 (seeFIG. 42) are attached as appropriate.

To form the truss structural members 100 into units, first, as shown inFIG. 49(a), the plurality of upper hubs 111 are arranged in range witheach other at predetermined intervals, and the upper hubs 111 and 111adjacent to each other are linked in order by the upper frame members112, and likewise, the plurality of lower hubs 121 are arranged in rangewith each other at predetermined intervals, and the lower hubs 121 and121 adjacent to each other are linked in order by the lower framemembers 122. To link the upper hubs 111 and the upper frame members 112,as shown in FIG. 44(a), the linking end parts 112 a of the upper framemembers 112 are fitted into the linking grooves 111 a of the upper hubs111, and to link the lower hubs 121 and the lower frame members 122, asshown in FIG. 44(b), the linking end parts 122 a of the lower framemembers 122 are fitted into the linking grooves 121 a of the lower hubs121.

Next, the upper hubs 111 and the lower hubs 121 are linked to each otherby lattice members 130 (see FIG. 49(a)). Namely, as shown in FIGS. 43through FIG. 45, the linking end part 130 a on one side of the latticemember 130 is fitted into a linking groove 111 a positioned adjacent tothe linking groove 111 a which the upper frame member 112 has beenjoined to among the five linking grooves 111 a of the upper hub 111, andthe other linking end part 130 a is fitted into the linking groove 121 apositioned adjacent to the linking groove 121 a which the lower framemember 122 has been joined to among the five linking grooves 121 a ofthe lower hub 121. At this point, since five linking grooves 111 a ofthe upper hub 111 and the five linking grooves 121 a of the lower hub121 are each arranged at 45-degree pitches (see FIG. 44), the latticemember 130 is inclined at 45 degrees with respect to the upper framemember 112 and the lower frame member 123.

Next, as shown in FIG. 49(a) and FIG. 49(b), the upper through member113 is covered from above the upper hubs 111 and the upper frame member112, and the tread receiving materials 150 are disposed to be the samein a position as that of the upper hub 111, and the upper hub 111, theupper through member 113, and the tread receiving member 150 areintegrally fixed by the bolt B1 and the nut N11.

The plurality of upper hubs 111 are integrated by the upper throughmember 113 and the rotation of the upper hubs 111 around their axes arerestrained, as a result, the weak axis directions of the trussstructural members 100, that is, the strength in the vertical directionof the staircase is reinforced. Namely, the bending rigidity in thein-plane direction of the truss structural members 100 is improved.

Likewise, the lower through member 123 is disposed along the lower hubs121 and the lower frame members 122, the tread receiving members 150 areset on the side end faces of the lower hubs 121, and the lower hubs 121,the lower through member 123, and the tread receiving members 150 arefixed integrally by bolts B11 and nuts N11. At this point, to the sideend faces on the outer sides of the lower hubs 121, washers 121 d areattached for preventing the lower frame members 122 and the latticemembers 130 from slipping outward (see FIG. 44(b)).

The plurality of lower hubs 121 are integrated by the lower throughmember 123 and the rotation of the lower hubs 121 around their axes arerestrained, as a result, the strength in the weak axis direction of thetruss structural members 100 is reinforced. Namely, the bending rigidityin the in-plane direction of the truss structural members 100 isimproved by the lower through members 123.

In addition, as shown in FIG. 49(b), support shoes 140 are attached toeach of the upper and lower ends of the upper chord members 110 and theupper and lower ends of the lower chord members 120.

As described above, the assembling of the truss structural members 100does not require welding or special tools, so that the assemblingbecomes easy and the number of parts for linking can be reduced, therebyproviding economic efficiency.

Furthermore, since the upper hubs 111 and the lower hubs 121 arearranged so that their axes are orthogonal to the truss planes, theout-of-plane direction of the truss structural members 100, that is, theside-to-side direction of the staircase in this embodiment becomes thestrong axis direction, and the truss structural members 100 have highstrength against external forces and deformation applied from the rightor left.

Furthermore, when the truss structural members 100 are assembled up tothe status mentioned above, the frame members 112 and 122 and thelattice members 130 are prevented from slipping out in the side-to-sidedirections of the hubs 111 and 121. Namely, even when the trussstructural members 100 are manufactured in advance at a factory, etc.,and are transported to an installation site, the members of the trussstructural members 100 do not slip out, and in addition, they can betransported while the plurality of truss structural members 100 arepiled up, thereby providing high transportation efficiency.

It is also possible that the treads 160 are attached to the trussstructural members 100 and 100 at a factory (that is, in the statusshown in FIG. 41). In this case, construction of the staircase iscompleted only by installing this unit to the building skeleton K.

As described above, according to the staircase of this embodiment,unlike conventional staircases that support the treads by massivemembers made of channel steel or I-shaped steel, the treads 160 aresupported by the truss structural members 100 that have a lightweightstructure and a sense of lightness in weight, thereby providing a senseof openness, and even when the staircase is installed indoors, itprovides no sense of oppression. Furthermore, the side end parts of thetreads 160 are fixed to the side end faces of the upper hubs 111 and theside end faces of the lower hubs 121, so that when this staircase isviewed from the side, as shown in FIG. 42 and FIG. 43, the side endfaces of the treads 160 are positioned within the side faces of thetruss structural members 100, and this provides a very simpleappearance.

Furthermore, the truss structural members 100 are structured so that theside end parts of the treads 160 are fixed to the side end faces of theupper hubs 111 and the side end faces of the lower hubs 121, as aresult, the upper chord members 110 and the lower chord members 120 arelinked to each other by the treads 160 (see FIG. 43). Namely, since theupper chord members 110 and the lower chord members 120 are tightlyintegrated with each other by the lattice members 130 and the treads160, the rigidity of the truss structural members 100 becomes very high.Furthermore, between the right and left truss structural members 100 and100, the upper hubs 111 are linked to each other and the lower hubs 121are linked to each other by the treads 160, so that displacement anddeformation of the upper hubs 111 and the lower hubs 121 in theout-of-plane directions of the truss planes are restricted. Namely,between the right and left truss structural members 100 and 100, theupper chord members 110 are linked to each other and the lower chordmembers 120 are linked to each other by the treads 160 (see FIG. 41),and shearing deformation of the plane formed by the right and left upperchord members 110 and 110 and the plane formed by the right and leftlower chord members 120 and 120 is restrained, as a result, thedevelopment of twisting and rolling when people go up and down thestaircase are greatly reduced.

Furthermore, the upper hubs 111 and the lower hubs 121 are formed ofidentical members, and the upper frame members 112 and the lower framemembers 122 are formed of identical members, so that the number of partsis small and productivity is high.

The truss structural members 100 of the staircase shown in FIG. 41through FIG. 50 have upper through members 113 in the upper chordmembers 110, and have lower through members 123 in the lower chordmembers 120, however, like in the truss structural member 100 of thestaircase shown in FIG. 51, it is also possible that the upper chordmember 110 comprises a plurality of short-length upper frame members 112provided in series in the direction of the staircase inclination and theupper hubs 111 that link the upper frame members 112 adjacent to eachother in the direction of the staircase inclination, and the lower chordmember 120 comprises a plurality of short-length lower frame members 122provided in series in the direction of the staircase inclination andlower hubs 121 that link the lower frame members 122 adjacent to eachother in the direction of the staircase inclination.

Such a structure makes it possible to easily adjust the lengths of theupper chord members 110 and the lower chord members 120. Namely, tochange the number of treads, the numbers of upper frame members 112 andthe lower frame members 122 are only changed.

Furthermore, like in the truss structural member 100 shown in FIG.52(a), it is also possible that the upper chord member 110 comprises aplurality of upper hubs 111 provided in series in the direction of thestaircase inclination and a long-length upper through member 113 fixedto the upper hubs, and the lower chord member 120 comprises a pluralityof lower hubs 121 provided in series in the direction of the staircaseinclination and a long-length lower through member 123 fixed to thelower hubs. In addition, it is also possible that, as shown in FIG.52(b), a hollow part 113 c is formed in the upper through member 113 anda hollow part 123 c is formed in the lower through member 123 toincrease the strength.

Such a structure makes it easy to manufacture the truss structuralmember since the number of parts forming the truss structural member 100is reduced.

Furthermore, it is also possible that, for example, the upper chordmember 110 comprises an upper through member 113 and a plurality ofupper hubs 111 and the lower chord member 120 comprises a plurality oflower frame members 122 and lower hubs 121 that link the lower framemembers although their illustration is omitted. These can be properlydetermined in consideration of the strength and design, etc., requiredfor the staircase.

In addition, the tread receiving members 150 of each of the staircasesshown in FIG. 41 through FIG. 52 are attached for each hub, however,like the tread receiving members 150 of the staircase shown in FIG.53(a) and FIG. 53(b), it is also possible that the tread receivingmembers 150 are laid across the upper hubs 111 and the lower hubs 121adjacent to each other in the cross direction. In this case, the treadreceiving members 150 have lengths that enable them to be laid acrossthe upper hubs 111 and the lower hubs 121 adjacent to each other in thecross direction, and are fixed to the side end faces of the upper hubs111 and the side end faces of the lower hubs 121.

Furthermore, the treads 160 of the staircases shown in FIG. 41 throughFIG. 52 are attached to the tread receiving members 150 via the jointmembers 162, however, the structure is not limited to this, and it isalso possible that, like the treads 160 of the staircase shown in FIG.53(a) and FIG. 53(b), the plate members 161 are directly attached to thetop faces of the tread receiving members 150.

Such a structure makes it easy to manufacture the staircase since thenumber of parts forming the staircase is reduced, since the upper hubs111 and the lower hubs 121 are linked to each other by the treadreceiving members 150, the strength of the truss structural members 100is increased.

Furthermore, in each of the staircases shown in FIG. 41 through FIG. 52,the treads 160 are attached via the tread receiving members 150 attachedto the side end faces of the hubs, however, the structure of the treadreceiving members 150 is not limited to this, and for example, like thetread receiving members 150′ shown in FIG. 54(a), it is also possiblethat the tread receiving member 150 comprises a front side horizontalmember 155 laid between the upper hubs 111 and 111 adjacent in theside-to-side direction, and a rear side horizontal member 156 laidbetween the lower hubs 121 and 121 adjacent in the side-to-sidedirection. In this case, the treads 160 are fixed to the top faces ofthe front side horizontal members 155 and the top faces of the rear sidehorizontal members 156.

Herein, the front side horizontal member 155 is a hollow extruded memberwith a rectangular section, and both ends thereof are externally fittedto receiving pieces 157 and 157 fixed to the side end faces of the rightand left upper hubs 111 and 111, whereby the front side horizontalmember 155 is fixed to the side end face of the upper hub 111. Likewise,the rear side horizontal member 156 is a hollow extruded member with arectangular section, and both ends thereof are externally fitted toreceiving pieces 157 and 157 fixed to the side end faces of the rightand left lower hubs 111 and 111, whereby the rear side horizontal member156 is fixed to the side end face of the lower hub 121. Furthermore, thereceiving pieces 157 of the upper chord member 110 side are fixed to theside end faces of the upper hubs 111 together with the upper throughmember 113, and likewise, the receiving pieces 157 of the lower chordmember 120 side are fixed to the side end faces of the lower hubs 121together with the lower through member 123.

In such a structure, since the tread 160 is supported by the front sidehorizontal member 155 laid between the right and left upper chordmembers 110 and 110 and the rear side horizontal member 156 laid betweenthe right and left lower chord members 120 and 120, the flexure at thecenter of the tread 160 is reduced. Namely, since the strength of thetread 160 itself can be low, the degree of freedom in structure andmaterial selection of the tread 160 increases.

Furthermore, like the treads 160 shown in FIG. 55(a) and FIG. 55(b), itis also possible that the tread 160 itself is formed of a hollowextruded member, and both ends thereof are directly externally fitted toand fixed to the receiving pieces 157 and 157. Namely, it is possiblethat the side end parts of the tread 160 are directly fixed to the sideend face of the upper hub 111 and the side end face of the lower hub121.

In such a structure, the number of parts forming the staircase isreduced, so that manufacturing becomes easy.

When a staircase with a slope of an angle other than 45 degrees isconstructed, the arrangement of the linking grooves is changed in eachhub. Namely, among the linking grooves 111 a of the upper hub 111 (seeFIG. 45), the angles between the linking grooves 111 a to which thelattice members 130 are linked and the linking grooves 111 a to whichthe upper frame members 112 are linked are set to be equal to the angleof the slope of the staircase. For example, when the slope of thestaircase is 40 degrees, the angle between the linking grooves 111 a and111 a is set to 40 degrees.

Furthermore, as shown in FIG. 56, it is possible to cope with changes inthe slope of the staircase by making the heights of the tread receivingmembers 150 to be attached to the upper hubs 111 different from theheights of the tread receiving members 150 to be attached to the lowerhubs 121. In this case, by adjusting the axis directions of the latticemembers 130 by folding the tip parts of the lattice members 130 towardpredetermined directions, the treads 160 and the lattice members 130become parallel to each other when the staircase is seen from the side.

Tenth Embodiment

The staircase according to the tenth embodiment of the present inventionwill be described with reference to FIG. 57 through FIG. 68.

First, the entire structure of the staircase according to the tenthembodiment will be described with reference to FIG. 57 through FIG. 60.

FIG. 57 is a perspective view of the staircase as a whole according tothe tenth embodiment of the present invention, FIG. 58 is a front viewof the same, FIG. 59 is a side view of the same, and FIG. 60 is anenlarged view of FIG. 59.

As shown in FIG. 57 through FIG. 60, the staircase according to thetenth embodiment of the present invention has a space truss structuralmember 210 as an intermediate stringer, and is mainly composed of thespace truss structural member 210 inclined with the slope of thestaircase; a plurality of brackets 206 disposed at each riser height;and treads 207 supported by the space truss structural member 210 viathe brackets 206. As shown in FIG. 59 and FIG. 60, the space trussstructural member 210 is fixed on the floor face F1 lower floor via thesupport shoes S1 and S2 attached at its bottom end, and fixed on thebeam member F21 supporting the floor face F2 upper floor via the supportshoes S3 attached on its top end. In addition, in the presentembodiment, the side ends of the treads 207 are fixed on the wall faceW, and a handrail 209 is provided on the other side ends.

Next, the space truss structural member will be described with referenceto FIG. 61 through FIG. 65.

FIG. 61 is an exploded perspective view of the staircase according tothe tenth embodiment of the present invention, FIG. 62(a) is a view seenfrom the direction of the arrows X1-X1 of FIG. 59; FIG. 62(b) is a viewseen from the direction of the arrows X2-X2 of FIG. 59; FIG. 63 is aview to show the frame members, the linking frame members, and thelattice members; FIG. 64 is an exploded perspective view to show thestate of assembling the hubs as the node members, and the frame membersand the linking frame members to be joined with the hubs; and FIG. 65 isa plan view of the same.

The space truss structural member 210, as shown in FIG. 61 and FIG. 62,is composed of two parallel upper chord members 210A and 210A;frame-shaped linking frame members 203 for linking the upper chordmembers 210A and 210A with each other; a single lower chord member 210Bdisposed below the midpoint between the upper chord members 210A and210A; and lattice members 204 for linking the upper chord members 210Aand 210A with the lower chord member 210B.

The upper chord members 210A and 210A are each composed of a pluralityof frame members 201 linked to each other via hubs 202A which are nodemembers, and the lower chord member 210B is composed of a plurality offrame members 201 linked to each other via hubs 202B. Thus, theplurality of frame members 201 can be linked together in thelongitudinal direction to compose the upper chord members 210A.

Since the hubs 202A composing the upper chord members 210A and the hubs202B composing the lower chord member 210B have the same structure,these hubs are referred with “202” in the description common to both ofthem.

The frame members 201 are made by processing hollow extrusions ofaluminum alloy with a circular cross section, and as shown in FIG. 63(a)and FIG. 63(b) are each provided with flat-shaped linking end parts 201a on both ends.

The linking end parts 201 a of the frame members 201 are formed byapplying press working or the like to both ends of the hollowextrusions, and can be fit into the linking grooves 202 a (See FIG. 64)of the hubs 202 described later. The linking end parts 201 a, as shownin FIG. 63(b), have notches at their tips in the direction orthogonal tothe axis of the frame members 201. Since they are long flattened in theaxial direction of the hubs 202 (See FIG. 64), the linking end parts 201a have a joint structure strong against the external force in the axialdirection of the hubs 202.

The hubs 202, as shown in FIG. 64, are column-shaped, and are eachprovided with a plurality of linking grooves 202 a carved on their outersurface along the axial direction of the hubs 202, and with a boltinsertion hole 202 b formed in the center on the end face. The hubs 202are extrusions of aluminum alloy, and the linking grooves 202 a and thebolt insertion holes 202 b are formed when the aluminum alloy isextruded. It is also possible to form the hubs 202 by casting.

The linking grooves 202 a of the hubs 202, as shown in FIG. 65, have thesame cross sectional shape as the tip parts of the linking end parts 201a of the frame members 201 so as to be engaged with the linking endparts 201 a. On the inner walls of the linking grooves 202 a areprovided with notches which are supposed to be engaged with the notchesof the linking end parts 201 a. In the present embodiment, eight linkinggrooves 202 a are formed radially, and adjacent linking grooves 202 aform a center angle of 45 degrees; however, it is possible to change theshape of the hubs 202, the number of linking grooves 202 a and the likein accordance with the number and angle of the members to be joined withthe hubs 202.

As shown in FIG. 64, of the linking grooves 202 a, those which are notjoined with the frame members 201, the linking frame members 203, or thelattice members 204 are filled with groove-filling members 202 e havingthe same size and shape as the linking grooves 202 a. In the presentembodiment, the length of the linking grooves 202 a of the hubs 202 ismatched with the length (width) of the linking end parts 204 a of thelattice members 204, and therefore, for example, when the frame members201 are inserted down to the bottom ends of the hubs 202, there areclearances in the above portions in the grooves 202 a. In this case,groove-filling members 202 f are inserted above the linking end parts201 a of the frame members 201 so as to prevent the dislocation of theframe members 201 joined.

When the frame members 201 are joined with the hubs 202, the notchesformed on the linking end parts 201 a of the frame members 201 can befit into the linking groove 202 a from the top face side (or the bottomface side) of the hubs 202. At this time, no welding or special toolsare required, thereby providing high in workability. In order to fill inthe fine clearances developed between the linking grooves 202 a and thelinking end parts 201 a, it is also possible to pour glue or the likeinto the linking grooves 202 a.

When the linking end parts 201 a of the frame members 201 are fit intothe linking grooves 202 a of the hubs 202, as shown in FIG. 65, thenotches formed on each of the linking grooves 202 a and the linking endparts 63 a are engaged with each other, which prevents the frame members201 from being pulled out in the axial direction.

In addition, on the top and bottom faces of the hubs 202B composing thelower chord member 210B are fixed washers 202 d so as to prevent theframe members 201 and the lattice members 204 from being pulled out. Thewashers 202 d are fixed with through bolts B17 which are inserted intothe bolt insertion holes 202 b of the hubs 202B, and nuts N17. On thetop and bottom faces of the hubs 202B are attached caps 202 c forcovering the bolts B17 and the nuts N17.

On the other hand, the hubs 202A composing the upper chord members 210Aare provided with brackets 206 on their top faces (See FIG. 60), and thewashers 202 d are attached exclusively on the bottom faces.

The linking frame members 203, like the frame members 201 shown in FIG.63(a) and FIG. 63(b), are made by processing hollow extrusions ofaluminum alloy, and have flat-shaped linking end parts 203 a at theirboth ends. The linking end parts 203 a have notches at their tips whichhave the same cross sectional shape as the linking end parts 201 a ofthe frame members 201 so as to be fit into the linking grooves 202 a ofthe hubs 202.

Like the frame members 201, the lattice members 204 are made byprocessing hollow extrusions of aluminum alloy, and as shown in FIG.63(c) and FIG. 63(d), have flat-shaped linking end parts 204 a at theirboth ends. The linking end parts 204 a have notches at their tips in thedirection which forms an angle α (hereinafter referred to as the coinangle α) with respect to the axis of the lattice members 204. Thelinking end parts 204 a have the same cross sectional shape as thelinking end parts 201 a of the frame members 201 so as to be press fitinto the linking grooves 202 a of the hubs 202. The lattice members 204are joined with the hubs 202 in such a manner that their axial directionhas an inclination of the coin angle α with respect to the axialdirection of the hubs 202.

FIG. 66(a) is a cross sectional view taken along the line X3-X3 of FIG.59; FIG. 66(b) is a view seen from the direction of the arrows X4-X4 ofFIG. 59 (the space truss structural member is seen from the direction ofthe slope of the staircase, and the brackets and treads are seen fromthe direction of the front of the staircase); FIG. 67(a) is aperspective view of the bracket; and FIG. 67(b) is a side view of thesame.

The brackets 206 installed on the upper chord members 210A and 210A arehollow extrusions of aluminum alloy with a polygonal cross section, andas shown in FIG. 67(a) and FIG. 67(b), are provided with treadsupporting faces 206 a to support the treads 207 on their top faces, andthe attachment faces 206 b on their bottom faces, which are laid on thetop faces of the hubs 202A of the upper chord members 210A.

The attachment faces 206 b are inclined with the slope of the staircasewith respect to the tread supporting faces 206 a. In other words, whenthe attachment faces 206 b are laid on the top faces of the hubs 202A,the tread supporting faces 206 a become horizontal (See FIG. 60).

The openings of the brackets 206 are closed by the lid members 206 c(See FIG. 60).

In the present embodiment, as shown in FIG. 66(b), adjacent upper chordmembers 210A and 210A are linked to each other via the brackets 206.

The treads 207 are plate members made of wood or metal, and as shown inFIG. 66(a) and FIG. 66(b), are fixedly supported on the tread supportingfaces 206 of the brackets 206. In the present embodiment, there areplates 207 a buried inside the treads 207 to screw the bolts B16.

FIG. 68(a), FIG. 68(b), and FIG. 68(c) are side views of the supportshoes.

The support shoes S1, as shown in FIG. 68(a), are each composed of afloor contact face S11 which comes into contact with the floor face F1lower floor; a hub contact face S12 which comes into contact with thebottom face of the hub 202A; and a locking piece S13 for positioning andfixing the hub 202A. As shown in FIG. 60, the support shoes S1 aredisposed between the bottom faces of the lowermost hubs 202A of theupper chord members 210A and the floor face F1 lower floor. The hubcontact faces S12 are inclined with the slope of the staircase withrespect to the floor contact faces S11.

The support shoe S2, as shown in FIG. 68(b), is composed of a floorcontact face S21 which comes into contact with the floor face F1 lowerfloor; a hub contact face S22 which comes into contact with the bottomface of the hub 202B; and a locking piece S23 for positioning and fixingthe hub 202B. As shown in FIG. 60, the support shoe S2 is disposedbetween the bottom face of the lowermost hub 202B of the lower chordmember 210B and the floor face F1 lower floor. The hub contact face S22is inclined with the slope of the staircase with respect to the floorcontact face S21.

The support shoes S3, as shown in FIG. 68(c), are each composed of abeam contact face S31 which comes into contact with the side face of thebeam member F21 supporting the floor face upper floor; a hub contactface S22 which comes into contact with the bottom face of the hub 202A;and a locking piece S33 for positioning and fixing the hub 202A. Asshown in FIG. 60, the support shoes S3 are each disposed between thebottom face of the uppermost hub 202A of the upper chord member 210A andthe side face of the beam member F21. The hub contact faces S22 areinclined with the slope of the staircase with respect to the beamcontact faces S31.

The support shoes S1 and S2, and S3 are extrusions of aluminum alloy.The shapes of these support shoes are not restricted to thoseillustrated, and can be modified according to the situation of theinstalling site of the staircase.

The constructing process of the staircase according to the tenthembodiment of the present invention will be described with reference toFIG. 59 through FIG. 62, FIG. 64, and FIG. 66.

First, the constructing process of the space truss structural member 210will be described as follows. The space truss structural member 210, asshown in FIG. 61, can be constructed by joining the frame members 201,the linking frame members 203, and the lattice members 204 with the hubs202A, and joining the frame members 201 and the lattice members 204 withthe hubs 202B.

With reference to FIG. 62(a) and FIG. 62(b), the constructing process ofthe space truss structural member 210 will be described in detail.First, four of the lattice members 204 are joined with one of the hubs202B composing the lower chord member 210B at a pitch of 90 degrees. Atthis time, the lattice members 204 are joined with the hubs 202 in sucha manner that they are inclined by the coin angle α with respect to theaxis of the hubs 202B because the linking end parts 204 a of the latticemembers 204 form the coin angle α (See FIG. 63(d)). After preparing aplurality of such units and aligning them, the frame members 201 aresequentially joined with adjacent hubs 202B and 202B so as to composethe lower chord member 210B. Furthermore, the upper ends of the adjacentlattice members 204 and 204 are linked to each other via the hubs 202A.Then, the frame members 201 are joined with the hubs 202A, 202A adjacentin the axial direction to compose the upper chord members 210A, and theframe members 203 are joined with the hubs 202A, 202A adjacent in thedirection orthogonal to the axis, thereby linking the two upper chordmembers, 210A and 210A with each other.

As a result of this assembly, the lower chord member 210B is locatedblow the midpoint between the upper chord members 210A and 210A, whichmakes the space truss structural member 210 look like an invertedtriangle when viewed in the axial direction (See FIG. 66(b)). When thespace truss structural member 210 is viewed from the side, it looks likea Warren truss (See FIG. 59).

As the result of the assembly, the axes of the hubs 202A and the axes ofthe hubs 202B orthogonally cross the axes of the frame 1. In otherwords, the axes of the hubs 202A orthogonally cross the upper chordmembers 210A, and the axes of the hubs 202B orthogonally cross the lowerchord members 210B. Thus, the hubs 202A and the hubs 202B are arrangedin such a manner that their linking grooves 202 a and the bolt insertionholes 202 b (See FIG. 64) are orthogonal to the direction of the slopeof the staircase. The end faces of the hubs 202A and the hubs 202B areinclined with the slope of the staircase.

In addition, the assembling process of the space truss structural member210 can be modified, without being restricted to the one describedbefore.

After the space truss structural member 210 is constructed, as shown inFIG. 60, the brackets 206 are laid on the top faces of the hubs 202A ofthe upper chord members 210A, and the through bolts B15 are insertedinto the bolt insertion holes 202 b from the bottom face side of thehubs 202A, so as to fix the brackets 206 on the top faces of the hubs202A. On the bottom face side of the hubs 202A are attached washers 202d (See FIG. 64) for preventing pulling out.

As shown in FIG. 64, the washers 202 d for preventing the pulling out ofthe frame members 201 and the lattice members 204 are applied on the topand bottom faces of the hubs 202B of the lower chord member 210B andfixed with the through bolts B17 and the nuts N17. In addition, thethrough bolts B17 and the nuts N17 are covered with caps 202 c.

Next, the space truss structural member 210 is laid between the floorboard F1 lower floor and the beam member F21 upper floor (See FIG. 59).In this case, between the bottom faces of the hubs 202A located at thebottom end of the upper chord members 210A and the floor face F1 lowerfloor are disposed support shoes S1, and between the bottom face of thelowermost hub 202B located at the lower chord member 210B and the floorface F1 lower floor is disposed a support shoe S2, respectively, andbetween the uppermost hubs 202A of the upper chord members 210A and thebeam member F21 upper floor are disposed support shoes S3.

When the space truss structural member 210 is laid at a prescribedstaircase slope, the tread supporting faces 206 a of the brackets 206become horizontal.

Then, the treads 207 are laid on the tread supporting faces 206 a, andthe bolts B16 are screwed into the plates 207 a which are buried in thetreads 207 from inside the brackets 206, thereby fixing the brackets 206and the treads 207. When necessary, as shown in FIG. 66(a) and FIG.66(b), side ends of the treads 207 are fixed to the receiving members208 installed on the wall face W.

Finally, the handrail 209 is installed on the side ends of the treads207 to complete the constructing of the staircase.

The aforementioned constructing process of the staircase is one exampleand can be modified. The space truss structural member 210 can beassembled either in the factory beforehand, or at the installing site ofthe staircase. In either case, the space truss structural member can beconstructed easily and accurately only by assembling the aforementionedmembers which have been previously formed to have the prescribed shapesand sizes.

Thus, staircases can be constructed only by fitting or bolt joining themembers which have been formed in the prescribed sizes and shapes. Thisis because no complicated process is necessary at a building site, andno special tools or welding is necessary, which enables unskilledworkers to construct staircases. In addition, the number of componentsfor linking can be reduced, which is economical.

Furthermore, using the space truss structural member 210 as theintermediate stringer makes the staircase lighter in weight thanconventional staircases which use heavy members such as channel steel orI-shaped steel, thereby facilitating handling during construction. Inparticular, making the space truss structural member 210 and thebrackets 206 of an aluminum alloy can realize the constructing of alighter-weight staircase because of the advantages of aluminum alloywhich is lightweight for its strength and is not corrosive. Therefore,such a staircase can be used with the floor structure of conventionalwooden houses.

It is also possible to easily control the length of the staircase as awhole (the number of steps) by increasing or decreasing the number offrame members 201 to be linked in the upper chord members 210A and thelower chord member 210B. When the staircase slope is different, all thatmust be done is to replace the brackets 206 with those matching thestaircase slope. Thus, staircases having a different number of steps orslopes can be constructed without changing the sizes or shapes of theframe members 201, the hubs 202, the linking frame members 203, and thelattice members 204, that is, the respective members to compose thespace truss structural member 210 can be mass manufactured so as toimprove production efficiency.

Since they are supported in the center parts, the treads 207 developminor flexure. Fixing the side ends of the treads 207 at the wall face Was in the present embodiment further stabilizes the treads 207, and thepresence of the wall face W on a side of the treads 207 givespedestrians on the staircase a sense of safety.

The space truss structural member 210 is composed of the two upper chordmembers 210A and the single lower chord member 201B, which forms aninverted triangle (See FIG. 66(b)) when viewed from the direction of theslope of the staircase, providing a simplified appearance. Furthermore,the truss structure provides a sense of lightness in weight andopenness, without obstructing the field of vision more than necessary,thereby creating a bright and clean indoor space with no sense ofoppression. In addition, the space truss structural member 210 isprevented from locating above the treads 207 because the brackets 206are fixed on the top faces of the upper chord member 210A and 210A ofthe space truss structural member 210, and the treads 207 are fixedlysupported on the top faces of the brackets 206, which provides asimplified appearance. Therefore, for example, as shown in FIG. 57, whenthe staircase according to the present embodiment is constructed alongthe wall face W, the wall face and the truss structural member 210 donot overlap with each other above the treads 207, which maintains theappearance of the staircase.

Since the displacement and deformation the side-to-side direction of theupper chord members 210A and 210A of the space truss structural member210 are restrained by the linking frame members 203, the torsionalrigidity of the entire staircase and the flexural rigidity theside-to-side direction are improved, which greatly reduces thedevelopment of twisting or rolling of the staircase when people aregoing up and down the staircase.

Eleventh Embodiment

The staircase according to an eleventh embodiment of the presentinvention will be described in detail with reference to FIG. 69 throughFIG. 72. The same components as those in the staircase according to thetenth embodiment are referred to with the same reference symbols, andthe overlapping description will be omitted.

FIG. 69 is an exploded perspective view of the staircase according tothe eleventh embodiment of the present invention; FIG. 70(a) is a planview to show the arrangement of the upper chord members and the linkingframe members of the space truss structural member composing thestaircase according to the second embodiment of the present invention;FIG. 70(b) is a plan view to show the arrangement of the lower chordmember and the lattice members of the same; FIG. 70(c) is a side view ofthe space truss structural member; FIG. 71 is a side view of thestaircase according to the first embodiment of the present invention;and FIG. 72 is an enlarged view of FIG. 71. FIG. 70(a) is a view seenfrom the direction of the arrows X5-X5 of FIG. 71, and FIG. 70(b) is aview seen from the direction of the arrows X6-X6 of FIG. 71.

As shown in FIG. 69 through FIG. 72, the staircase according to theeleventh embodiment of the present invention has a space trussstructural member 220 as an intermediate stringer, and is composed ofthe space truss structural member 220 inclined with the slope of thestaircase; a plurality of brackets 206 disposed at each riser height;and treads 207 supported by the space truss structural member 220 viathe brackets 206. As shown in FIG. 71 and FIG. 72, the space trussstructural member 220 is fixed on the floor face F1 lower floor via thesupport shoes S1 and S2 attached at its bottom end, and fixed on thebeam member F21 supporting the floor face F2 upper floor via the supportshoes S3 attached on its top end. In the present embodiment, there arehandrails 209 on both the right and left side ends. The brackets 206,the treads 207, and the handrails 209 have the same structures as thosedescribed in the tenth embodiment, so a detailed description will beomitted.

The space truss structural member 220, as shown in FIG. 69 and FIG. 70,is composed of two parallel upper chord members 220A and 220A; linkingframe members 203 and linking diagonal members 205 for linking the upperchord members 220A and 220A with each other; a single lower chord member220B located below the midpoint of the upper chord members 220A and220A; and lattice members 204 for linking the upper chord members 220Aand 220A and the lower chord member 220B together.

The upper cord members 220A and 220A are each composed of a plurality offrame members 201 linked via hubs 222A which are node members, whereasthe lower chord member 220B is composed of a plurality of frame members210 linked via hubs 222B. The frame members 201, the linking framemembers 203, and the lattice members 204 have the same structures asthose described in the tenth embodiment, so a detailed description willbe omitted.

The linking diagonal members 205 like the frame members 201 shown inFIG. 63(a) and FIG. 63(b), are made by processing hollow extrusions ofaluminum alloy, and have flat-shaped linking end parts at their bothends. The linking end parts have notches at their tips which have thesame cross sectional shape as the linking end parts 201 a of the framemembers 201 so as to be fit into the linking grooves of the hubs 222A.The linking frame members 203 are orthogonal to the upper chord members220A and 220A, whereas the linking diagonal members 205 are diagonal tothe upper chord members 220A and 220A. To be more specific, as shown inFIG. 70(a), on the top face of the space truss structural member 220 areformed rectangular frame bodies by the frame members 201 composing theupper chord members 220A and the linking frame members 203 linking theright and left upper chord members 220A. And the linking diagonalmembers 205 are arranged on the diagonals of the frame bodies in astaggered arrangement, thereby forming a truss on the top face of thespace truss structural member 220 in cooperation with the upper chordmembers 220A and 220A, and the linking frame members 203.

The hubs 222A and 222B have the same structure as the hubs 202 shown inFIG. 64 except that linking grooves (having the same structure as thelinking grooves 202 a described in the tenth embodiment) are formed ontheir outer surface exclusively in the directions that join the framemembers 201, the linking frame members 203, the lattice members 204 orthe linking diagonal members 205. Such a structure can prevent unusedlinking grooves from being exposed so as to make the groove-fillingmembers 202 e (See FIG. 64) unnecessary, which provides a simplifiedappearance.

As shown in FIG. 70(a) and FIG. 70(b), the lattice members 204 and thelinking diagonal members 205 are arranged in the same direction in aplan view; in this case, the hubs 222A composing the upper chord members220A are made long-sized (See FIG. 70(c)), and the lattice members 204and the linking diagonal members 205 are sequentially joined in the samelinking grooves.

Thus disposing the linking diagonal members 205 on the diagonals of theframe bodies formed by the frame members 201 and the linking framemember 203 on the top face of the space truss structural member 220 cangreatly improve the torsional rigidity and the flexural rigidity(particularly the side-to-side direction) of the space truss structuralmember 220, which greatly reduces the shearing deformation of theseframe bodies. Thus, it becomes possible to greatly reduce thedevelopment of twisting or rolling of the staircase when an unbalancedload is applied while people are going up and down the staircase.

As shown in FIG. 72, the space truss structural member 220 is fixed onthe floor face F1 lower floor via the support shoes S1 and S2 attachedat its bottom end, and fixed on the beam member F21 supporting the floorface F2 upper floor via the support shoes S3 attached on its top end.The support shoes S1 and S2, and S3 shown in FIG. 72 are different inthe whole shape from the support shoes shown in FIG. 68; however, themain parts have the same structure.

To be more specific, the support shoes S1 are each composed of a hubcontact face which comes into contact with the bottom face of the hub222A, and a floor contact face which comes into contact with the floorface F1 lower floor; and the support shoe S2 is composed of a hubcontact face which comes into contact with the bottom face of the hub222B, and a floor contact face which comes into contact with the floorface F1 lower floor. And the support shoes S3 are each composed of a hubcontact face which comes into contact with the bottom face of the hub222A, and a beam contact face which comes into contact with the sideface of the beam member F21 supporting the floor face upper floor. Thesehub contact faces are inclined with the slope of the staircase.

The staircase according to the eleventh embodiment describedhereinbefore, similar to the staircase according to the tenthembodiment, has a simplified appearance, thereby providing a sense oflightness in weight and openness without obstructing the field of visionmore than necessary, which results in a bright and clean indoor spacewith no sense of oppression. Furthermore, the torsional rigidity of andthe flexural rigidity the side-to-side direction are high, therebyproducing no twisting or rolling of the staircase when people are goingup and down the staircase is slight. In other words, the stability ofthe treads 207 can be secured only by the space truss structural member220, without fixing the treads 207 on the wall face, which enables thestaircase to be installed in a desired site.

When the brackets 206 are regarded as structural members, it is possibleto dispense with the linking frame members 203 and to link the upperchord members 220A and 220A with each other via the linking diagonalmembers 205 only.

In the aforementioned embodiments, the space truss structural member iscomposed of two upper chord members and a single lower chord memberlinked to each other via the lattice members. However, the number ofupper chord members and the number of lower chord members are notrestricted to these; as shown in a twelfth embodiment which will bedescribed later, the space truss structural member can be composed of alarger number of upper chord members and lower chord members.

Twelfth Embodiment

The staircase according to a twelfth embodiment of the invention isdescribed in detail with reference to FIG. 73 and FIG. 74. The sameelements as those of the staircases according to the embodimentsdescribed above are attached with the same symbols, and overlappingdescription will be omitted.

Herein, FIG. 73 is an exploded perspective view of the staircaseaccording to the twelfth embodiment of the invention, and FIG. 74 showsa view of the space truss structural member of the staircase shown inFIG. 73 seen from the direction of the staircase inclination and thebrackets and the treads seen from the staircase front side.

The staircase according to the twelfth embodiment of the inventioncomprises, as shown in FIG. 73, a space truss structural member 230inclining with the slope of the staircase, a plurality of brackets 231disposed at each of the heights of the risers, and treads 207 supportedby the space truss structural member 230 via the brackets 231. The spacetruss structural member 230 is fixed to the floor face of the lowerfloor via support shoes attached to the lower ends of the trussstructural member (see FIG. 68(a) and FIG. 68(b)), and are fixed to beammembers supporting the floor face of the upper floor via support shoes(see FIG. 68(c)) attached to the upper end of the truss structuralmember. In addition, as shown in FIG. 74, in this embodiment, the sideends of the treads 207 are fixed to the wall face W, and the other sideends are attached with a handrail 209. The treads 207 and the handrail209 are structured similarly to those described in the tenth embodiment,so that a detailed description thereof is omitted. In addition, it ispossible that the treads are not fixed to the wall face W and thisapplies to the above-described embodiments.

The space truss structural member 230 comprises, as shown in FIG. 73 andFIG. 74, three upper chord members 230A parallel to each other, lowerchord members 230B positioned below the midpoints of adjacent ones ofthe upper chord members 230A and 230A, linking frame members 203 thatlink the adjacent upper chord members 230A to each other and link theadjacent lower chord members 230B, and lattice members 204 that link theupper chord members 230A and the lower chord members 230B to each other.

Namely, the space truss structural member 230 has three upper chordmembers 230A and two lower chord members 230B, and as shown in FIG. 74,it is roughly trapezoid when seen from the direction of the staircaseinclination.

The upper chord member 230A comprises a plurality of frame members 201linked to each other by hubs 202A, and the lower chord member 230Bcomprises a plurality of frame members 201 linked to each other by hubs202B. The frame members 201, the hubs 202A and 202B, the linking framemembers 203, and the lattice members 204 are structured similarly tothose described in the tenth embodiment, so that a detailed descriptionthereof is omitted.

The bracket 231 is structured similarly to the bracket 206 shown in FIG.67 except for a different length, so that a detailed description thereofis omitted.

When the space truss structural member 230 is thus structured, thetreads 207 can be more stably supported than in the case of the spacetruss structural member 210 of the tenth embodiment.

Furthermore, to support treads wider than the treads 207, by linkingmore upper chord members 230A and lower chord members 230B to the sidesof the upper chord members 230A and the lower chord members 230B, thetreads are easily supported. Since the lower chord members 230B arepositioned below the midpoints of adjacent ones of the upper chordmembers 230A, the number of lower chord members is always one less thanthe number of upper chord members 230A.

Furthermore, even when upper chord members of more than three and lowerchord members of more than two are used to form the space trussstructural member, the simplified appearance is still obtained, therebyproviding a sense of lightness in weight and openness withoutobstructing the field of vision more than necessary, which results in abright and clean indoor space with no sense of oppression.

Thirteenth Embodiment

The staircase according to the thirteenth embodiment of the invention isdescribed in detail with reference to FIG. 75 and FIG. 76. The sameelements as those of the staircases according to the above-describedembodiments are attached with the same symbols, and overlappingdescription is omitted.

Herein, FIG. 75 shows a view of the space truss structural member of thestaircase according to the thirteenth embodiment of the invention seenfrom the direction of the staircase inclination, and the brackets andthe treads seen from the front side of the staircase, and FIG. 76 is aside view of the same.

As shown in FIG. 75 and FIG. 76, the staircase according to thethirteenth embodiment of the invention comprises a space trussstructural member 240 inclining with the slope of the staircase, aplurality of brackets 231 disposed at each riser height, and treads 207supported by the space truss structural member 240 via the brackets 231.Furthermore, the space truss structural member 240 is fixed to the floorface F1 of the lower floor via support shoes S1 and S2 attached to thelower end thereof, and are fixed to beam members F21 that support thefloor face F2 of the upper floor via support shoes S3 attached to theupper end. Furthermore, as shown in FIG. 75, in this embodiment, theside ends of the treads 207 are fixed to the wall face W, and the otherside ends are attached with a handrail 209. Furthermore, the treads 207,the handrail 209, and the support shoes S1, S2, and S3 are structured inthe same manner as those described in the tenth embodiment, so that adetailed description thereof is omitted.

The space truss structural member 240 comprises, as shown in FIG. 75 andFIG. 76, three upper chord members 240A parallel to each other, lowerchord members 240B positioned below the midpoints of adjacent ones ofthe upper chord members 240A and 240A, linking frame members 203 thatlink the adjacent upper chord members 240A to each other and link theadjacent lower chord members 240B to each other, and lattice members 204that link the upper chord members 240A and the lower chord members 240Bto each other, and furthermore, at the midpoint of the upper floor faceF2 and the lower floor face F1, a second lower chord member 240C isdisposed below the midpoint of the adjacent lower chord members 240B and240B, and the lower chord members 240B and 240B are linked to each otherby the lattice members 204.

Namely, the space truss structural member 240 has three upper chordmembers 240A and two lower chord members 240B, and further has onesecond lower chord member 240C at the midpoint of the upper floor faceF2 and the lower floor face F1.

The upper chord members 240A are formed of a plurality of frame members201 linked by the hubs 202A, the lower chord members 240B are formed ofa plurality of frame members 201 linked by the hubs 42B, and the secondlower chord member 240C is formed of a plurality of frame members 201linked by the hubs 42C. In addition, the frame members 201, the hubs202A, the linking frame members 203, and the lattice members 204 arestructured in the same manner as those described in the tenthembodiment, so that a detailed description thereof is omitted.

The brackets 231 are structured similarly to the brackets 206 shown inFIG. 67 except for a different length, so that a detailed descriptionthereof is omitted.

The hubs 242B are structured similarly to the hubs 202 shown in FIG. 64,however, two lattice members 204 are linked to one linking groove, sothat the lengths of the hubs 242B are longer than that of the hubs 202.In other points, their structure is similar to that of the hubs 202, sothat a detailed description thereof is omitted. The hubs 242C arestructured similarly to the hubs 202, so that a detailed descriptionthereof is omitted.

Thus, according to the staircase of the thirteenth embodiment, thebending rigidity (in particular, in the vertical direction) of the spacetruss structural member 240 is improved by disposing the second lowerchord member 240C below the midpoint of the lower chord members 240B and240B. Therefore, flexure of the space truss structural member 240 isgreatly restrained.

In addition, the space truss structural member 240 shown in FIG. 75 hasthree upper chord members 240A, two lower chord members 240B, and onesecond lower chord member 240C, as a result, it has a shape of aninverted triangle, however, for example, when the number of upper chordmembers 240A is four, the number of lower chord members 240B becomesthree and the number of second lower chord members 240C becomes two, sothat the space truss structural member 240 becomes trapezoid although itis not shown. Furthermore, when the number of upper chord members 240Ais two, the number of lower chord members 240B becomes one, so that onlyone second lower chord member 240C is provided immediately below thelower chord member 240B.

Fourteenth Embodiment

The staircase according to the fourteenth embodiment of the invention isdescribed in detail with reference to FIG. 77. The same elements asthose of the staircases according to the above-described embodiments areattached with the same symbols, and overlapping description is omitted.

Herein, FIG. 77 is an exploded perspective view of the staircaseaccording to the fourteenth embodiment of the invention.

The staircase according to the fourteenth embodiment is constructed byarranging a plate member 251 on the top face of the space trussstructural member 210 of the staircase of the tenth embodiment describedabove and fixing this plate member 251 to a plurality of hubs 202A.Namely, the upper chord members 210A and 210A adjacent to each other arelinked to each other by the plate member 251.

The space truss structural member 210 is the same as that described inthe tenth embodiment, so that a detailed description thereof is omitted.

The plate member 251 is formed of an aluminum alloy plate in which anumber of small holes are perforated, and is fixed to the top faces ofthe plurality of hubs 202A forming the upper chord members 210A. Theplate member 251 may be formed of a polycarbonate plate, an acrylicresin plate, or a wood plate.

According to the staircase of the fourteenth embodiment, the positionalrelationship of the plurality of hubs 202A is restricted by the platemember 251, as a result, shearing deformation of the plane (the top faceof the space truss structural member 210) formed by the plurality ofhubs 202A is restrained. Namely, by linking the right and left upperchord members 210A and 210A to each other by the plate member 251, theright and left upper chord members 210A and 210A are integrated, wherebyshearing deformation of the top face of the space truss structuralmember 210 (plane formed by the upper chord members 210A and 210A) isrestrained, as a result, the development of twisting and rolling on thespace truss structural members 210 and 210 when people go up and downthe staircase is greatly reduced.

Furthermore, since deformation of the top face of the space trussstructural member 210 is restrained by the plate member 251, thestructure of the linking frame members 203 and the brackets 206 can belightened in weight. Furthermore, when deformation of the top face ofthe space truss structural member 210 is sufficiently restrained only bythe plate member 251, the linking frame members 203 can be omitted.

In addition, the plate members 251 can be attached across the wholelength of the upper chord members 210A or attached to a part of theupper chord members. It is also possible that a plurality of platemembers are arranged in a spaced manner in the direction of thestaircase inclination although this is not illustrated.

Fifteenth Embodiment

The staircase according to the fifteenth embodiment is described indetail with reference to FIG. 78 through FIG. 80. The same elements asthose of the above-described embodiments are attached with the samesymbols, and overlapping description thereof is omitted.

Herein, FIG. 78(a) and FIG. 78(b) are exploded perspective views of thestaircase according to the fifteenth embodiment of the invention. InFIG. 78(a), the brackets and treads are omitted. FIG. 79(a) shows a viewof the space truss structural member seen from the direction of thestaircase inclination and the brackets and treads seen from the frontside of the staircase (corresponding to the view seen from the directionof the arrows X4-X4 of FIG. 59). FIG. 79(b) shows a modified example ofthe staircase according to the fifteenth embodiment, and FIG. 80(a),FIG. 80(b), and FIG. 80(c) show modified examples of the same.

The staircase according to the fifteenth embodiment is constructed sothat, as shown in FIG. 78(a), upper reinforcing members 261A arearranged along the upper chord members 210A of the space trussstructural member 210 of the staircase of the tenth embodiment describedabove and are fixed to serial three or more hubs 202A forming the upperchord member 210A, and lower reinforcing members 261B are arranged alongthe lower chord members 210B and are fixed to serial three or more hubs202B forming the lower chord member 210B. Namely, along the upper chordmembers 210A and the lower chord members 210B, upper reinforcing members261A and lower reinforcing members 261B are arranged so as to reinforcethe strength in the weak axis direction of the linked parts of the hubs.

The space truss structural member 210 is the same as that described inthe tenth embodiment, so that a detailed description thereof is omitted.

The upper reinforcing members 261A and the lower reinforcing members261B are flat plates 261 (so-called flat bars) made of an aluminum alloyas shown in FIG. 78(a), and in this embodiment, they have the samelengths as the whole lengths of the upper chord members 210A and thelower chord members 210B, respectively. In the flat plate 261, aplurality of bolt holes are perforated according to the hubs 202A (hubs202B).

The flat plate 261 does not always have high rigidity in the verticaldirection (plate thickness direction), however, it has high rigidity inthe side-to-side direction (width direction), and therefore, therigidity in the side-to-side direction of the upper chord members 210Aand the lower chord members 210B can be sufficiently increased.

To fix the upper reinforcing members 261A (flat plate 261) to the topfaces of the hubs 202A forming the upper chord members 210A, as shown inFIG. 78(a), the upper reinforcing members 261A are placed on the topfaces of the hubs 202A, and as shown in FIG. 78(b), brackets 206 areplaced on the top faces of the upper reinforcing members 261A, and thenbolts (not shown) are inserted from the bottoms of the hubs 202A throughthe upper reinforcing members 261 to the insides of the brackets 206 andfastened by nuts (not shown). In this case, the brackets 206 are alsosupported and fixed onto the top faces of the upper reinforcing members261A by the bolts and nuts.

In addition, to fix the lower reinforcing member 261B (flat plate 261)to the bottom faces of the hubs 202B forming the lower chord member210B, as shown in FIG. 78(a), bolts (not shown) are inserted from thebottom faces to the top faces of the hubs 202B while the lowerreinforcing member 261B is made to contact with the bottom faces of thehub 202B and are fastened by nuts (not shown). As shown in FIG. 79(a),when the lower reinforcing member 261B is disposed, the lowerreinforcing member 261B comes into contact with the bottom faces of thehubs 202B and prevents the frame members 201 and the lattice members 204from slipping downward, so that the washer 202 d shown in FIG. 64 can beomitted.

According to the staircase of the fifteenth embodiment, the plurality ofhubs 202A forming the upper chord members 210A are integrated by theupper reinforcing members 261A, and the bending rigidity in theside-to-side direction (weak axis direction) of the upper chord members210 is increased, as a result, rolling when people go up and down thestaircase can be greatly reduced. Namely, by integrating at least threehubs 202A by the upper reinforcing member 261A, at least the middle hub202A is reinforced in the direction of rotation around its axis, so thatthe bending rigidity of the upper chord members 210 in the side-to-sidedirection is increased, and deformation in the side-to-side direction isrestrained.

In addition, since the bending rigidity of the lower chord members 210Bin the side-to-side direction (weak axis direction) is also increased bythe lower reinforcing member 261B, torsional rigidity of the trussstructural member is increased, whereby twisting and rolling when peoplego up and down the staircase are greatly restrained.

Furthermore, as in this embodiment, by using the upper reinforcingmembers 261A having lengths across the whole lengths of the upper chordmembers 210A and the lower reinforcing member 261B having a lengthacross the whole length of the lower chord member 210B, the space trussstructural member 210 is reinforced across the whole length, and forexample, it is possible that the structure of the linking frame members203 and the brackets 206 is lightened in weight, and furthermore, it isalso possible that the linking frame members 203 are omitted. In thecase where the linking frame members 203 are omitted, like the spacetruss structural member 210′ shown in FIG. 79(b), the right and leftupper chord members 210A and 210A are linked to each other by thebrackets 206.

The forms of the upper reinforcing members 261A and the lowerreinforcing members 261B are not limited to those shown in FIG. 79(a)and FIG. 79(b).

For example, like the upper reinforcing members 261A shown in FIG.80(a), the upper reinforcing members may be formed of members 262 eachhaving an L-shaped section, and like the lower reinforcing member 261B,the lower reinforcing member may be formed of a member 263 having agroove-shaped section with a top face opened.

The member 262 having an L-shaped section is composed of an upper plate262 a arranged along the upper side of the upper chord member 210A, anda side plate 262 b hung down from the side end part of the upper plate,and is shaped into an L in its section. In this case, the upper plate262 a contributes to improvement in rigidity in the side-to-sidedirection of the upper chord member 210A. Furthermore, the side plate262 b has a primary role to improve the design of the staircase sideface by covering the side face of the upper chord member 210A as well asa role to improve the rigidity in the vertical direction of the upperchord member 210A. Namely, since the clearance between the frame member201 and the upper plate 262 a is covered by the side plate 262 b, asimplified design is obtained.

The member 263 having a groove-shaped section is formed into a grooveshape in its section by a lower plate 263 disposed along the lower sideof the lower chord member 210B and side plates 263 b and 263 b stood upalong the inclination direction of the lattice member 204 from both sideends of the lower plate. In this case, the lower plate 263 a contributesto improvement in rigidity in the side-to-side direction of the lowerchord member 210B. In addition, the side plates 263 b and 263 b have aprimary role to improve the design of the staircase side faces bycovering the side faces of the lower chord member 210B as well as a roleof improvement in rigidity in the side-to-side direction of the lowerchord member 210B. Namely, since the clearance between the frame member201 and the lower plate 263 a is covered, a simplified design isobtained.

Furthermore, the above-described upper reinforcing members 261A and thelower reinforcing member 261B are provided mainly for improvement inrigidity in the side-to-side direction of the upper chord members 210Aand the lower chord member 210B, and it is also possible that upward anddownward loads are positively allotted to the reinforcing members 261Aand 261B.

For example, as shown in FIG. 80(b), when the member 264 having a hollowpart 264 a is used as the upper reinforcing member 261A, the sectionalproperties of the member 264 are high, so that rigidity can be improvednot only in the side-to-side direction but also in the verticaldirection. Furthermore, as shown in FIG. 80(c), a member partiallyhaving a hollow part 265 a may be disposed so that the hollow part 265 ais positioned by the side of the upper chord member 210A (or the lowerchord member 210B). Since the member 265 shown in FIG. 80(c) has ahollow part 265 a at the side, not only is the rigidity of the upperchord member 210A improved in the side-to-side direction and thevertical direction, but also the upper chord member 210A is covered bythe hollow part 265 a, so that a simplified design is obtained for theside face of the staircase.

Furthermore, it is preferable that the upper reinforcing members 261Aand the lower reinforcing member 261B are provided across the wholelengths of the upper chord members 210A or the lower chord member 210B,however, in the case where each reinforcing member is composed of aplurality of short-length members, the short-length members are fixed toserial three or more hubs 202, and preferably, the continuous parts ofthe short-length members are over lapped on the hubs 202, and furtherpreferably, the continuous parts are overlapped on serial two hubs 202.For example, in the case where the upper chord member 210A is composedof ten hubs 202A and nine frame members 201 (see FIG. 59) and the upperreinforcing member 261A is composed of two short-length members, it ispreferable that each short-length member is formed into a length thatmakes it possible to fix the short-length member to the serial six hubs202A, one short-length member is fixed to the six hubs 202A from below,and another short-length member is fixed to the six hubs 202A fromabove, and the end parts of the short-length members are overlapped onthe serial two hubs 202A. Thereby, even when the upper reinforcingmember 261A is composed of a plurality of short-length members, thereinforcing effect at the same level as in the case where the upperreinforcing member 261A is composed of one long-length member isobtained.

Sixteenth Embodiment

The staircase according to the sixteenth embodiment of the invention isdescribed in detail with reference to FIG. 81 through FIG. 83. The sameelements as those of the above-described embodiments are attached withthe same symbols, and overlapping description thereof is omitted.

Herein, FIG. 81(a) and FIG. 81(b) are exploded perspective views of thestaircase according to the sixteenth embodiment of the invention. InFIG. 81(a), the brackets and treads are omitted. FIG. 82 is a side viewof FIG. 81(b), and FIG. 83(a) is a view seen from the direction of thearrows X7-X7 of FIG. 82 (a view of the space truss structural memberseen from the staircase inclination direction and the bracket and treadsseen from the front side of the staircase). FIG. 83(b) and FIG. 83(c)show modified examples of the staircase according to the sixteenthembodiment.

The staircase according to the sixteenth embodiment comprises, as shownin FIG. 81(b) and FIG. 82, a space truss structural member 270 incliningwith the slope of the staircase, a plurality of brackets 206 disposed ateach riser height, and treads 207 supported by the space trussstructural member 270 via the brackets 206.

The space truss structural member 270 comprises two upper chord members270A and 270A parallel to each other, frame-shaped linking frame members203 that link the upper chord members 270A and 270A to each other, onelower chord member 270B positioned below the midpoint of the upper chordmembers 270A and 270A, lattice members 204 that link the upper chordmembers 270A and 270A and the lower chord member 270B to each other.

The lower chord member 270B has the same structure as that of the lowerchord member 210B of the staircase of the tenth embodiment, and theframe members 201, the hubs 202, the linking frame members 203, and thelattice members 204 are also identical to those described in the tenthembodiment, so that a detailed description thereof is omitted.

The upper chord member 270A is formed of a member 71 having a groovepart 271 a that opens at its side face of the lower chord member 270Bside and the hubs 202A are housed inside the groove part 271 a as shownin FIG. 81(a) and FIG. 83(a). Namely, in the staircase according to thetenth embodiment shown in FIG. 61, the upper chord member 210A is formedby providing a plurality of short-length frame members 201 in series inthe lengthwise direction, however, in the staircase according to thesixteenth embodiment, the upper chord member 270A is formed of along-length member 271. The hubs 202A are attached inside the member271.

The member 271 is an extruded member made of an aluminum alloy, and asshown in FIG. 81(a), on the lower chord member 270B side, it has agroove part 271 a whose face opposite the other upper chord member 270Ais opened. The groove part 271 a continues in the direction of thestaircase inclination. In greater detail, as shown in FIG. 83(a), themember 271 is formed of an upper plate 271 c and a lower plate 271 d, aside plate 271 e linking the side ends of these upper and lower plates,and a partition plate 271 f that links the midpoint of the upper plate271 c to the midpoint of the lower plate 271 d. In addition, the groovepart 271 a is formed by the upper plate 271 c, the lower plate 271 d,and the partition plate 271 f, and the hollow part 271 b is formed bythe upper plate 271 c, the lower plate 271 d, the side plate 271 e, andthe partition plate 271 f. The member 271 is very light in weight sincethe inside is hollow, and furthermore, the upper plate 271 c and thelower plate 271 d are linked by the partition plate 271 f at theirmidpoints, so that the sectional structure of the member is strongagainst vertical loads.

Next, the procedures for constructing the staircase according to thesixteenth embodiment are described with reference to FIG. 81(a) and FIG.81(b).

First, four lattice members 204 are linked to the hubs 202B forming thelower chord member 270B at pitches of 90 degrees. In this case, sincethe linking end parts 204 a of the lattice members 204 have the coinangle α (see FIG. 63(d)), the lattice members 204 are linked with aninclination of α with respect to the axes of the hubs 202B. After aplurality of units thus formed are assembled and arranged in range witheach other, the frame members 201 are linked to adjacent hubs 202B and202B in turn to form the lower chord member 210B, and the upper ends ofthe adjacent lattice members 204 and 204 are further linked by the hubs202A.

Next, as shown in FIG. 81(a), the members 271 are covered on theplurality of hubs 202A from the sides, and the plurality of hubs 202Aare housed inside the groove parts 271 a of the members 271, whereby theupper chord members 270A are formed. In this case, the bolt insertionholes 202 b of the hubs 202A (see FIG. 64) and the bolt insertion holesof the members 271 are aligned with each other.

Thereafter, as shown in FIG. 81(b), the brackets 206 are placed on thetop faces of the upper chord members 270A (upper plates 271 c of themembers 271). Then, bolts (not shown) are inserted from the bottom facesides of the upper chord members 270A to the insides of the brackets 206and fastened by nuts (not shown), whereby the hubs 202A, the members271, and the brackets 206 are fixed integrally.

Then, this unit is carried to a staircase installation site, and theunit is installed so as to incline with a predetermined slope of thestaircase, and thereafter, the treads 207 are supported and fixed ontothe tread supporting faces 206 a of the brackets 206 and handrails,etc., are arranged as appropriate, whereby construction is completed.

According to the staircase of the sixteenth embodiment, the upper chordmembers 270A are formed of the members 271 having groove parts 271 a andthe plurality of hubs 202A are housed inside the groove parts 271 a, sothat as shown in FIG. 82, the design of the side faces of the staircaseis simplified. Furthermore, since the upper chord member 270A is formedof one long-length member 271, no weak axis exists. Namely, the upperchord members 270A are high in rigidity not only in the verticaldirection but also in the side-to-side direction, and therefore, astructure strong against rolling and twisting is obtained. As in thecase of the above-described embodiments, the construction of thestaircase does not require welding or special tools, thereby providinghigh workability.

In addition, the form of the member forming the upper chord member 270Ais not limited to that described above, and for example, like the member271′ shown in FIG. 83(b), it is possible that the hollow part 271 b′ isformed to be trapezoid to improve the design.

Furthermore, in the space truss structural members 270 shown in FIG.83(a) and FIG. 83(b), the hubs 202A are disposed so that their axes areorthogonal to the axes of the linking frame members 203, that is, thetop and bottom faces of the hubs 202A incline with the slope of thestaircase, however, like the hubs 202A′ of the truss structural members270′ shown in FIG. 83(c), it is possible that their axes crossdiagonally the axes of the linking frame members 203′. In this case, amember 272 that has, on the lower chord member 270B side, a groove partwhose face opposite the lower chord member 270B is opened, is used.

Furthermore, as shown in FIG. 83(b) and FIG. 83(c), it is possible thatthe above-described lower reinforcing member 261B is disposed along thelower chord member 270B.

In addition, the forms of the hubs 202 described in the first throughsixteenth embodiments are not limited to those illustrated, and they maybe formed into, for example, rectangular column shapes. The node membersare not limited to the structures using the above-described hubs 202,and it is also possible that the ball joint method is employed.

Seventeenth Embodiment

The staircase according to the seventeenth embodiment of the inventionis described with reference to FIG. 84 through FIG. 86. The sameelements as those of the above-described embodiments are attached withthe same symbols, and overlapping description thereof is omitted.

Herein, FIG. 84 is a perspective view in which a part of the staircaseof the seventeenth embodiment of the invention is omitted, FIG. 85(a) isa view of the space truss structural member of FIG. 84 seen from thedirection of the staircase inclination, FIG. 85(b) is a side view ofFIG. 84, FIG. 86 is a perspective view showing a linking frame memberand a lattice member.

The staircase according to the seventeenth embodiment comprises, asshown in FIG. 84, a space truss structural member 280 inclining with theslope of the staircase, a plurality of brackets 206 disposed at eachriser height, and treads 207 supported by the space truss structuralmember 280 via the brackets 206.

The space truss structural member 280 comprises two upper chord members280A and 280A parallel to each other, linking frame members 283 thatlink the upper chord members 280A and 280A to each other, one lowerchord member 280B positioned below the midpoint of the upper chordmembers 280A and 280A, and lattice members 284 that link the upper chordmembers 280A and 280A and the lower chord member 280B to each other.

The upper chord member 280A is formed of, as shown in FIG. 85(a), amember 281 that has a connection piece 281 a projecting toward the lowerchord member 280B and a connection piece 281 b projecting toward theadjacent upper chord member 280A. The top face of the upper chord member280A is formed to be flat (hereinafter, referred to as a bracketsupporting face 281 c). The member 281 is a hollow extruded member madeof an aluminum alloy, and the connection pieces 281 a and 281 b areformed integrally when the aluminum alloy is extruded. In the connectionpieces 281 a and 281 b, bolt insertion holes are perforated at properintervals.

The lower chord member 280B is formed of, as shown in FIG. 85(a), amember 282 having two connection pieces 282 a and 282 a projectingtoward the upper chord members 280A. The member 282 is a hollow extrudedmember made of an aluminum alloy, and the connection pieces 282 a and282 a are formed integrally when the aluminum alloy is extruded.

The linking frame members 283 are frame-shaped as shown in FIG. 86, andare formed by processing a hollow extruded member with a circularsection made of an aluminum alloy. Both ends thereof are pressed flat(hereinafter, referred to as flat end parts 283 a). In the flat endparts 283 a, bolt insertion holes 283 b are perforated.

The lattice members 284 have the same structure as that of the linkingframe members 283 described above, and have flat end parts 284 a on bothends, and in the flat end parts 284 a, bolt insertion holes 284 b areperforated.

Next, construction procedures of the staircase according to theseventeenth embodiment are described with reference to FIG. 84 and FIG.85.

First, the members 281 forming the upper chord members 280A and themember 282 forming the lower chord member 280B are arranged and linkedto each other by a plurality of lattice arranged zigzags. Namely, asshown in FIG. 85(b), the upper chord members 280A, the lower chordmember 280B, and the lattice members 284 form a warren truss.

To link the upper chord members 280A (members 281) and the latticemembers 284 to each other, as shown in FIG. 85(a), the flat end parts284 a of the lattice members 284 are made to contact with the connectionpieces 281 a of the members 281, and are fixed by bolts and nuts afterthe bolt insertion holes 284 b of the flat end parts 284 a (see FIG. 86)are aligned with the bolt insertion holes (not shown) of the connectionpieces 281 a. Furthermore, as shown in FIG. 84, among the latticemembers 284, the flat end parts 284 a of some members come into contactwith the outsides of the connection pieces 281 a, and the flat end parts284 a of other members come into contact with the insides of theconnection pieces 281 a, and these members are alternately arranged. Inaddition, as shown in FIG. 85(a), the flat end parts 284 a of thelattice members 284 positioned outside the connection pieces 281 a andthe flat end parts 284 a of the lattice members 284 positioned insidethe connection pieces 281 a are fixed so as to overlap each other viathe connection pieces 281 a. The method for linking the lower chordmember 280B (member 282) and the lattice members 284 is also the same.

Next, adjacent upper chord members 280A and 280A are linked to eachother by the linking frame members 283. To link the upper chord members280A (members 281) and the linking frame members 283 to each other, asshown in FIG. 85(a), the flat end parts 283 a of the linking framemembers 283 are made to contact with the connection pieces 281 b of themembers 281, and are fixed by bolts and nuts after the bolt insertionholes 283 b of the flat end parts 283 a (see FIG. 86) are aligned withthe bolt insertion holes (not shown) of the connection pieces 281 a.

Next, as shown in FIG. 84, the brackets 206 are supported and fixed tothe bracket placing faces 281 c of the upper chord members 280A.

Then, this unit is carried to a staircase installation site andinstalled with a predetermined slope of the staircase, and then, thetreads 207 are supported and fixed to the tread supporting faces 206 aof the brackets 206 and handrails, etc., are attached as appropriate,whereby the construction of the staircase is completed.

According to the staircase of the seventeenth embodiment, the linkingbetween the upper chord members 280A and the lower chord member 280B iscarried out only by linking the flat end parts 284 a of the latticemembers 284 to the connection pieces 281 a of the upper chord members280 and the connection pieces 282 a of the lower chord member 280Bprojecting in the linking directions of the lattice members 284, andthis makes the assembly of the space truss structural member 280 easy.

In addition, since the connection pieces 281 a and 281 b of the upperchord members 280A and the connection pieces 282 a of the lower chordmember 280B are continued in their lengthwise directions, the degree offreedom in attaching positions of the linking frame members 283 and thelattice members 284 is high, and furthermore, it is possible to copewith changes in dimensions and shapes of the linking frame members 283and the lattice members 284.

Furthermore, the upper chord members 280A and the lower chord member280B are formed of each one of the long-length members 281 and 282, sothat no weak axis exits among them. Namely, the upper chord members 280Aand the lower chord member 280B are high in rigidity not only in thevertical direction but also in the side-to-side direction, so that astructure strong against rolling and twisting is obtained.

Eighteenth Embodiment

The staircase according to the eighteenth embodiment of the invention isdescribed with reference to FIG. 87 and FIG. 88. The same elements asthose of the above-described embodiments are attached with the samesymbols, and overlapping description thereof is omitted.

Herein, FIG. 87 is a perspective view partially omitting the staircaseaccording to the eighteenth embodiment of the invention, and FIG. 88 isa view of the space truss structural member of the staircase accordingto this embodiment seen from the direction of the staircase inclination.

The staircase according to the eighteenth embodiment comprises, as shownin FIG. 87, a space truss structural member 290 inclining with the slopeof the staircase, a plurality of brackets 206 disposed at each riserheight, and treads 207 supported by the space truss structural member290 via the brackets 206.

The space truss structural member 290 comprises a plate-shaped member291, one lower chord member 290B positioned below the midpoint of thismember 291, and lattice members 284 that link the member 291 and thelower chord member 290B to each other.

The member 291 is an extruded member made of an aluminum alloy, and asshown in FIG. 88, it has hollow parts 291 a and 291 b on the right andleft, and a plate part 291 b that links these hollow parts 291 a and 291a, and on the hollow parts 291 a, connection pieces 291 c projectingtoward the lower chord member 290B are formed.

Herein, the right and left hollow parts 291 a and 291 a correspond tothe two upper chord members 290A and 290A parallel to each other, andthe plate member 291 b corresponds to the plate member that links theright and left upper chord members 290A and 290A. Namely, the right andleft upper chord members 290A and 290A are extrusion-formed integrallywith the plate member that links them.

The lower chord member 290B is formed of a member 292 having twoconnection pieces 292 a and 292 a projecting toward the upper chordmembers 290A as shown in FIG. 88. The member 292 is a hollow extrudedmember made of an aluminum alloy, and the connection pieces 292 a and292 a are integrally formed when the aluminum alloy is extruded.

The method for linking the upper chord members 290A and the latticemembers 284 and the method for linking the lower chord member 290B andthe lattice members 284 are the same as those described in theseventeenth embodiment, so that a detailed description thereof isomitted.

According to the staircase of the eighteenth embodiment, the upper chordmembers 290A and 290A adjacent to each other are integrated in advance,so that the number of parts is reduced and construction of the spacetruss structural member 290 becomes easy.

Furthermore, in the space truss structural member, since the right andleft upper chord members 290A and 290A (hollow parts 291 a and 291 a)are linked to each other by the plate member (plate part 291 b), theshearing rigidity of the space truss structural member is very high, andsince the upper chord members 290A and the lower chord member 290B areformed of each one of the long-length members 291 and 292 among which noweak axis exists, the rigidity of the space truss structural member inthe side-to-side direction is high. Namely, the space truss structuralmember 290 is structured to be strong against rolling and twisting.

INDUSTRIAL APPLICABILITY

According to the staircase of the present invention, the treads aresupported by the truss structural members or the space truss structuralmember that have a lightweight structure with a sense of lightness inweight and create no sense of oppression even if the staircase isinstalled indoors. Furthermore, the lightness in weight of the staircasefacilitates its handling during construction, as compared with theconventional staircases composed of heavy members such as channel steelor I-shaped steel, thereby improving constructing efficiency.

In addition, not requiring special tools or welding facilitates theconstructing of the staircase. Furthermore, the members composing thetruss structural members or the space truss structural member are smallin number and can be commonly used even when the installing requirementsof the staircase are different. This feature is suitable for massproduction, providing high producing efficiency.

1. A staircase composed of: a pair of right and left stringers composedof truss structural members; and treads, wherein the truss structuralmembers are each composed of: an upper chord member and a lower chordmember which are inclined with the slope of the staircase; and aplurality of lattice members for linking the upper chord member and thelower chord member.
 2. The staircase according to claim 1, wherein thetruss structural members are linked to each other by treads.
 3. Thestaircase according to claim 1, wherein the plurality of lattice membersinclude a plurality of horizontal lattice members disposed horizontallyfor each riser, and the treads are supported by the horizontal latticemembers.
 4. The staircase according to claim 1, wherein the trussstructural members are linked to each other via a plurality of linkingmembers which are laid horizontally at each riser height, and the treadsare fixedly supported on the linking members.
 5. The staircase accordingto claim 4, wherein the linking members adjacent to each other in theheight direction are linked to each other.
 6. The staircase according toclaim 1, wherein the upper chord member and the lower chord member areeach provided with node members, and the lattice members are joined withthe node members.
 7. The staircase according to claim 6, wherein thenode members are column-shaped and each have linking grooves formed onthe outer surface thereof; the lattice members each have linking endparts formed on both ends; and the linking groove and the linking endparts have notches to be engaged with each other, and nodes are formedby press fitting the linking end parts into the linking grooves.
 8. Thestaircase according to claim 6, wherein at least either the upper chordmembers or the lower chord members are continued in the direction of thestaircase inclination and formed of members having groove parts openedto the lattice member side, and the node members are attached inside thegroove parts.
 9. The staircase according to claim 1, wherein the trussstructural members are each composed of node members each disposed at anode point; and frame members for linking adjacent node members.
 10. Thestaircase according to claim 9, wherein the node members arecolumn-shaped and each have linking grooves on an outer surface thereof;the frame members each have linking end parts on both ends; and thelinking groove and the linking end parts have notches to be engaged witheach other, and nodes are formed by press fitting the linking end partsinto the linking grooves.
 11. The staircase according to claim 9 furthercomprising a reinforcing member arranged along at least one of the upperchord member and the lower chord member, the reinforcing member beingfixed with at least three or more of the node members.
 12. The staircaseaccording to claim 1, wherein at least either between the right and leftupper chord members or between the right and left lower chord members, aplate member is attached.
 13. The staircase according to claim 1,further comprising: handrails positioned above the side end parts of thetreads, and balusters that have lower ends joined with the trussstructural members and support the handrails.
 14. A staircasecomprising: a pair of right and left truss structural members which areinclined with the slope of the staircase and a plurality of treadsdisposed between the truss structural members, wherein each trussstructural member is composed of an upper chord member having aplurality of column-shaped upper node members provided in series in thedirection of the staircase inclination, a lower chord member having aplurality of column-shaped lower node members provided in series in thedirection of the staircase inclination, and lattice members that linkthe upper chord member and the lower chord member to each other, eachupper node member and each lower node member are disposed so that theaxes thereof are orthogonal to the truss plane of the truss structuralmember, and on the outer circumferential faces thereof, a plurality oflinking grooves are formed along the axes, and the lattice member hasflat-shaped linking end parts that can fit into the linking grooves onboth ends, one of the linking end parts is fitted into the linkinggroove of the upper node member, the other one of the linking end partsis fitted into the linking groove of the lower node member, and the endsof each tread are fixed to the side end face of the upper node memberand the side end face of the lower node member.
 15. The staircaseaccording to claim 14, wherein the upper chord members have upper framemembers provided between the upper node members adjacent to each otherin the direction of the staircase inclination, and the upper framemembers have, on their both ends, flat-shaped linking end parts that canbe fitted into the linking grooves of the upper node members, and thelinking end parts are fitted into the linking grooves of the upper nodemembers.
 16. The staircase according to claim 14, wherein the lowerchord members have lower frame members disposed between the lower nodemembers adjacent to each other in the direction of the staircaseinclination, and the lower frame members have, on their both ends,flat-shaped linking end parts that can be fitted into the linkinggrooves of the lower node members, and the linking end parts have beenfitted into the linking grooves of the lower node members.
 17. Thestaircase according to claim 14, wherein the upper chord member has anupper through member having a length from the upper end to the lower endof the upper chord member, and the upper through member is attached tothe side end faces of the upper node members.
 18. The staircaseaccording to claim 14, wherein the lower chord member has a lowerthrough member having a length from the upper end to the lower end ofthe lower chord member, and the lower through member is attached to theside end faces of the lower node members.
 19. The staircase according toclaim 14, wherein the upper node members and the lower node members arepositioned at the same heights, tread receiving members are fixed to theside end faces of the upper node members and the side end faces of thelower node members, and the treads are fixed to the tread receivingmembers.
 20. The staircase according to claim 14, further comprising:handrails positioned above the side end parts of the treads, andbalusters the lower ends of which are joined to the truss structuralmember and supporting the handrails.
 21. A staircase in which treads aresupported by a space truss structural member inclined with the slope ofthe staircase, wherein the space truss structural member is formed bylinking a plurality of upper chord members linked to each other with alower chord member located below the midpoint of adjacent ones of theupper chord members via lattice members.
 22. The staircase according toclaim 21, wherein the space truss structural member further comprises asecond lower chord member below the aforementioned lower chord members,and the lower chord members and the second lower chord member are linkedto each other by lattice members.
 23. The staircase according to claim21, wherein the upper chord member and the lower chord member are eachformed by linking a plurality of frame members via node members.
 24. Thestaircase according to claim 23, wherein a reinforcing member isdisposed along at least either one of the upper chord member or thelower chord member of the space truss structural member, and thereinforcing member is fixed to three or more of successive node members.25. The staircase according to claim 23, wherein the lattice members andthe frame members each have linking end parts on both ends; on outersurfaces of the node members are formed linking grooves into which thelinking end parts can be fit; and the linking end parts are fit into thelinking grooves.
 26. The staircase according to claim 25, whereinadjacent ones of the upper chord members are linked to each other vialinking frame members, and the linking frame members each have linkingend parts on both ends, the linking end parts being fit into the linkinggrooves of the node members.
 27. The staircase according to claim 21,wherein the upper chord members have connection pieces that projecttoward the lower chord members and the lower chord members haveconnection pieces that project toward the upper chord members, thelattice members have flat end parts on their both ends, and one of theflat end parts is joined to the connection piece of the upper chordmember, and the other flat end part is joined to the connection piece ofthe lower chord member.
 28. The staircase according to claim 27, whereinthe upper chord members adjacent to each other are linked to each otherby the linking frame members, the linking frame members have flat endparts on both ends thereof, each of the upper chord members has aconnection piece projecting toward another adjacent upper chord member,and the flat end part of the linking frame member is joined to theconnection piece.
 29. The staircase according to claim 26, wherein thelinking frame members include linking diagonal members which arediagonal to each of the upper chord members.
 30. The staircase accordingto claim 21, wherein the upper chord member is formed of a member havinga groove part opened at its lower chord member side, where the groovepart houses the node members, and the lower chord member is formed bylinking a plurality of frame members by node members, and the latticemember and the frame member have linking end parts on their both ends,and on the outer faces of the node members, linking grooves into whichthe linking end parts can fit are formed, and the linking end parts arefitted into the linking grooves.
 31. The staircase according to claim21, wherein adjacent ones of the upper chord members are linked to eachother via brackets for supporting the treads.
 32. The staircaseaccording to claim 21, wherein the upper chord members adjacent to eachother are linked to each other by a plate member.